Solar Cells

Solar Cells

  • Rafik Karaman added an answer:
    6
    What about the stability of DSSC at high temperatures?

    is commercialization of DSSC possible?

    Rafik Karaman

    Dear Bulkesh Siwach,

    Regarding your question " With Solid electrolyte ..is efficiency remain same", the answer can be found in links 1-4 & 7 depicted in my first answer.

    Rafik

  • Abdelhalim Zekry added an answer:
    1
    Why PV industry migrated from Al2O3 passivation to TiO2 passivation for boron diffused emittter solar cell?

    Which passivation is best for boron diffused emitter solar cell?

    Abdelhalim Zekry

    Dear Vivek,

    The change to certain  materials or processes is dictated by the better functionality and less cost. It is so, that TiO2 passivization layers can act also as anti reflection coating while Al2O3 can serve as passivization layer only. Both are produced by the the atomic layer deposition technologist. So, titanium dioxide is preferable.

    For more information please return to the papers in the links; https://www.ise.fraunhofer.de/de/veroeffentlichungen/konferenzbeitraege/2009/24th-european-photovoltaic-solar-energy-conference-and-exhibition-hamburg-germany/benick_2bp.1.3.pdf

    and http://www.hindawi.com/journals/ijp/2013/431614/

    wish you success

  • Abdelhalim Zekry added an answer:
    5
    What Does this I-V curve means?

    In some samples, I get weird I-V curves. Can some one let me know what these means? Attaching Dark I-V and illuminated I-V.

    Device is ITO/PEDOT:PSS/P3HT:PCBM/Al

    + 1 more attachment

    Abdelhalim Zekry

    Welcome Ehsan,

    I think it is more common to use inverted inverted device structure where the ITO is contacted by ETL which are types of conduction transparent oxides and then comes the active organic bilayer followed by the HTL and the metal electrode.

    For more information please follow the link:http://www.sciencedirect.com/science/article/pii/S0079670013000427

    In the literature it is found that the ito layer can be patterned with a buffer layer to stabilize it against the pedot. You may find more information in the link:https://www.researchgate.net/profile/Martijn_Wienk/publication/234033689_Fabrication_of_PEDOT-OTS-patterned_ITO_substrates/links/00b4952bf

    wish you success

  • Santo Martinuzzi added an answer:
    5
    In dark my device has diode nature but the I-V curve in presence of light in fourth quardrent linear in nature.What may be the reasons?

    In antimony sulfide based solar cell I am getting low Fill Factor.How to improve this?

    Santo Martinuzzi

    dear colleague,

    You have probably an interfacial problem, a layer which contains a lot of trap centers located in the space charge region. In dark there is a barrier which results in a classical I-V curve. When illuminated the traps are emptied and the barrier disappears.  More information could result of the use of monochromatic light at various walengthes. May be you can localise the position of the traps in the band gap

  • Tony Maine added an answer:
    4
    What is market status of Dye solar cells?

    As i am working on DSSC and want to know about its commercializatio? Please add some references for same..

    Tony Maine

    The initial hope of DSSC was that the technology would be substantially cheaper to make than silicon. The very large drop in silicon prices has removed this hypothetical advantage. DSSC is now morphing into perovskite type cells. Maybe these will 'take off'.

  • Cai Yongmei asked a question:
    New
    How to avoid ghost plating on solar cell?

    we try to plate Ni/Cu/Ag on the solar cell, but has much ghost plating on there

  • Dallas Fisher added an answer:
    6
    Low fill factor (FF) in perovskite solar cells?

    What is the cause of low fill factor (FF) in methylammonium lead iodide perovskite solar cells? I am looking to improve the efficiency of my cells for further study.

    Structure is FTO/compact TiO2/MAPbI3/Spiro-OMeTAD/Au

    FF is 0.59, with Voc 1.01 V and Isc 24 mA/cm2 (with shadow mask). Cells are dry O2 annealed overnight to oxidize LiTFMS additive.

    TiO2 blocking layer is 35-40 nm, perovkite 250 nm, spiro-OMeTAD is 120 nm. Layers are compact, and perovskite does not appear to have pinholes. What can be done to further improve the FF in this situation?

    Thank you for your input and advice.

    Dallas Fisher

    Khan,

    I believe that you are correct. I have extrapolated Rs = 62 ohm-cm2 and Rsh = 160 ohm-cm2 for my top preforming cell (using 1/slope technique). The series resistance is much too high. (I was not successful using the Aberle model).

    I will ensure good lead connections to the VI meter, reducing contact resistance with conductive paste, and reducing spiro-OMeTAD thickness.

    The gold top contact is applied through thermal evaporation. SEM images show very good contact between all layers. My guess is that the low hole mobility of spiro-OMeTAD is hindering charge extraction.

  • Md Nadim Ferdous Hoque added an answer:
    14
    How can one measure current vs. time or voltage vs. time curves using a source-meter (keithley)?
    I need to measure voltage and current transients on my devices (solar cell, photodetector). Can this be done using a keithley sourcemeter? I have a 2602A series sourcemeter from Keithley (if that helps).
    Md Nadim Ferdous Hoque

    Hi,

    I know, it has been a year, but I faced the same issue and got the solution recently which I am sharing here. Keithley has this software for various models called 'KickStart Instrument Control Software' which do the job for I-t or V-t measurements. 

    The link is attached as well.

  • Marcelo Alatzatianou Rodrigues added an answer:
    6
    What spin coater would you recommend for research in perovskite solar cell field?

    Hello everyone!

    We are starting our lab focusing on planar and mesoscopic heterojunction based on CH3NH3PbI3, TiO2, spiro-OMeTAD and FTO/ITO substrates.

    • Could you recommend an equipent with good cost-benefit relation?
    • What kind of resources/characteristics should we pay attention on this equipment choice?

    Thank you very much for any comment!

    Marcelo Alatzatianou Rodrigues

    Krishna,

    Thanks! Their catalog looks interesting. Besides the spin-coater they have other useful stuff.

    Good suggestion!

  • Vladimir Kubov added an answer:
    12
    Parameter estimation of solar PV cells and modules?

    Dear All

    I am working on parameter estimation of solar PV cells and modules with metaheuristic optimisation algorithms. With a 26 pairs of I-V data and also with a 46 pairs of I-V dataset from a published paper, RMSE is low and parameters are successfully found. However,  with a 800 pairs of I-V points of a PV module, RMSE is around 0.28 that seems too high. Why this happens? It is due to the large size of used dataset? or I must apply any change when estimating parameters of PV modules rather than PV cells? And do you have any dataset of experimental I-V points of PV cells? I would like to use them as the case studies of my future paper.

    Thank you

    Kind Regards

    Ahmad

    Vladimir Kubov

    I have set of experimental data for solarbatteries. And I have set of SPICE-model parameters for Crystalline Silicon PV-battery. 

    The I(V)-curve for small Amorphous Silicon PV-battery is very differ from I(V)-curve for big Crystalline Silicon PV-battery. So simplest model with Photo-Current Source and Shunt Diode (classic Spice-model) is not suitable for Amorphous Silicon PV-battery.

  • Mirko Congiu added an answer:
    1
    How to decrease Rs value of Dye-sensitized Solar Cell (DSSC) device?

    I have prepared TiO2/MnO2 working electrode for DSSC device. The result shows poor performance (efficiency and FF). I think, the problem is Rs value unstable (too high). How to decrease Rs value and stabilize it?

    I attached the result of I-V characteristic

    Thanks

    Mirko Congiu

    Hi Adi,

    May be that the big value of resistance is due to a bad sintering of the nanoparticles (high resistance to the conduction of the photo-generated electrons through the porous film). In this case you should consider the internal resistance of your porous layer. I suggest you to use elecrochemical impedance spectroscopy (EIS) in order to investigate you system applying diffrent voltages near Voc in forward bias. In this way, you should understand which resistance value is responsible for the poor performance of your device. Try to fit your system using the transmission line equivalent circuit (Bisquert). You should optimize the experimental parameters of your experiment using a factorial design (design of experiments DOE) considering: the sintering temperature, the film´s thickness and the ratio between TiO2 and MnO2.

    p.s.

    in the attached publication, in the supporting information we used an equivalent circuit to fit the EIS response  of a complete DSSC

    Good luck

    Mirko

    • Source
      [Show abstract] [Hide abstract] ABSTRACT: In this work a novel preparation method is proposed for the one step synthesis and thin-film deposition of cost effective counter electrodes for dye sensitized solar cells (DSSC). This method is fast and allows depositing CoS nanoparticles onto F-doped SnO2 (FTO) substrates within 2 hours. The cost of reagents needed is significantly less than the cost of the products based on hexachloroplatinic acid used in the production of platinum transparent counter electrodes, and the method is compatible with the ink-jet and screen-printing technologies. The whole process does not require expensive equipment and is of simple implementation. Electrochemical Impedance Spectroscopy, Cyclic Voltammetry and I-V curves under simulated sunlight were used to characterize the electrode efficiency and stability. The counter electrodes prepared according to our procedure were transparent and show good catalytic activity with the I-/I3- redox couple in a high stability electrolyte for DSSC (HSE). Under the best deposition conditions the charge transfer resistance of the electrodes was 1.3 Ωcm2, less than that of the screen printed platinum on FTO glass (2.3 Ωcm2). Power conversion efficiencies up to 6.6% were reached using the CoS counter electrodes. The optimized CoS counter electrodes were demonstrated to work also with a ferrocene besed redox liquid electolyte.
      Full-text · Article · Nov 2014 · Electrochimica Acta
  • Reza Tohidifar asked a question:
    New
    Can anyone tell me why we should use photoresistor layers,like SU-8,in simulating solar cells with FDTD,Lumerical? Is that necessary?

    we should finally get rid of photo-resistor layers,so why we should use it in our simulations?

  • Savita Maurya added an answer:
    4
    How to draw semi log plot and double log plot to extract information from J-V plot?

    How to find solar cell parameters from I-V plot.send me some references

    Savita Maurya

    Hi,

    I got it form following paper. Please read it. Even if you have any problem you can ask me.

    A highly sensitive evaluation method for the determination of different current conduction mechanisms through dielectric layers

  • Jan-Martin Wagner added an answer:
    6
    Solar cell parameter extraction from a single I-V curve?

    I wrote a Matlab program to extract solar cell parameters (Rs, Rsh and n) from a single I-V curve using a simple diode model utilizing Lambert W equation [See the reference below].

    I have found that the values of Rs, Rsh and n is sensitive to range of I-V which we have selected. That is, if we select V from 0 to 1V then we will get some value for Rs, Rsh and n. However, if we select V value from -1 to 1 V then the value of Rs, Rsh and n will be different from the previous values.

    Could you please tell me is there any particular range of I-V for the calculation of Rs, Rsh and n values?

    Jan-Martin Wagner

    Please be aware that the effect of the series resistance varying along the I--V curve was already noted by Wolf & Rauschenbach in their 1963 paper "SERIES RESISTANCE EFFECTS ON SOLAR CELL MEASUREMENTS" (https://www.researchgate.net/publication/223585317_Series_resistance_effects_on_solar_cell_measurements); the full text is available from Sinton instruments (http://www.sintoninstruments.com/PDFs/wolf-aec61-seriesresitance-searchable.PDF).

    In their Fig. 9(a) the variation of the series resistance along the I--V curve is shown for one specific cell.

    • [Show abstract] [Hide abstract] ABSTRACT: Current-voltage characteristics of photovoltaic solar energy converter cells are obtainable by three methods, which yield different results due to the effects of the cell internal series resistance. The three resultant characteristics are: (1) the photovoltaic output characteristic, (2) the p-n junction characteristic, and (3) the rectifier forward characteristic. Choice of the proper method is necessary for obtaining the correct information for the individual application.Most frequently used, e.g. for the determination of solar converter performance, is the photovoltaic output characteristic. A quick way is described for deriving such a characteristic for any light level from a corresponding characteristic obtained at a different light level. This method involves two translations of the coordinate system and requires only the knowledge of the series resistance and the difference in light intensities or short circuit currents.An inversion of this method permits an easy determination of the series resistance, involving measurements at two arbitrary light levels of unknown magnitude.The effects of series resistance consist at high light levels in a flattening of the photovoltaic output characteristic and a related drop in the maximum power point voltage. The resultant decrease in efficiency has to be overcome by series resistance reduction for solar cell applications with optical concentrators or for space missions in closer sun-proximity. In cell portions progressively further distant from the contact strip increasing cell voltages develop, approaching open circuit condition at very high light intensities. This yields a reduction of current contribution from those portions of the cell and a deviation from the normal proportionality between short circuit current and light intensity.The direct measurability of the p-n junction characteristic at high current densities without series resistance effects by the second method provides a powerful tool to the device development engineer, besides yielding a second method for the determination of the series resistance. Results from the application of this method indicate that, in the current density range as used in solar energy conversion, the silicon solar cell characteristic is much more closely described by the diffusion theory for p-n junctions than was previously believed.ZusammenfassungStrom-Spannungs-Charakteristiken von photoelektrischen Sonnen-energie-Umwandlern kann man nach drei verschiedenen Methoden erhalten. Durch den Einfluss des Innenwiderstandes der Zellen liefert jede ein anderes Ergebnis. Die drei resultierenden Charakteristiken sind: (1) Die photoelektrische Ausgangs-Charakteristik, (2) die p-n-(Übergang-Charakteristik and (3) die Gleichrichter-Durchlass Charakteristik. Um die für die individuelle Anwendung richtige Information zu erhalten, muss in jedem Fall die geeignete Methode ausgewählt werden.In den meisten Fällen wird die photoelektrische Ausgangs-Charakteristic benutzt, z.B. für die Bestimmung der Leistung von Sonnenenergie-Umwandlern. Es wird eine Methode beschrieben, die es gestattet, eine solche Charakteristick für eine beliebige Lichtintensität aus einer entsprechenden anderen mit davon verschiedener Lichtintensität rasch herzuleiten. Die Methode benutzt zwei Koordinaten-Transformationen und erfordert nur die Kenntnis des Innenwiderstandes und die Abhängigkeit der Kurzschluss-Ströme von der Intensität.Eine Umkehrung dieser Methode erlaubt eine einfache Bestimmung des Innenwiderstandes. Dazu genügen Messungen bei zwei beliebigen Intensitäten unbekannter Grösse.Die Wirkung des Innenwiderstandes bei hohen Lichtintensitäten besteht in einer Abflachung der photoelektrischen Ausgangs-Charakteristic und damit einem Abfall der Spannung bei der grössten Leistung. Die daraus resultierende Verkleinerung des Wirkungsgrades muss bei Anwendung von optischen Konzentratoren oder bei Verwendung im Weltraum in grösserer Sonnennahe durch Erniedrigung des Innenwiderstandes ausgeglichen werden. In Zellenbereichen grbsseren Abstands vom Kontaktstreifen whähst die Spannung an und erreicht bei grossen Intensitäten fast die Verhältnisse beim offenen Stromkreis. Das bedingt eine Stromverdrängung von diesen Bereichen der Zelle und eine Abweichung von der normalen Proportionalität von Kurzschluss-Stom und Lichtintensität.Die direkte Messbarkeit der p-n-Übergang-Charakteristik nach der zweiten Methode ohne Innenwider- standseffekte bei hohen Stromdichten erweist sich als hervorragendes Werkzeug für den Entwicklungsingtenieur und liefert daneben noch eine zweite Möglichkeit für die Bestimmung des Innenwiderstandes.Die Ergebnisse der Anwendung dieser Methode zeigen, dass die Charakteristik der Silizium-Photozelle im Stromdichte-Bereich der Sonnenbatterien durch die Diffusionstheorie für p-n-Übergänge weit besser beschrieben wird, als man früher angenommen hatte.RésuméLes caractéristiques Intensité-Tension des cellules de convertisseurs d'énergie solaire photovoltaïques peuvant être obtenues par trois méthodes qui donnent des résultats différents par suite des effets de résistance intérieure en série des cellules. Les trois caractéristiques résultantes sont: (1) la caractéristique de rendement photovoltaïque, (2) la caractéristique de jonction p-n, et (3) la caractéristique de redresseur (vers l'avant). Pour obtenir le renseignement correct relatif à l'application particulière, il est nécessaire de choisir la méthode appropriée.La caractéristique de rendement photovoltaïque est utilisée tr`es fréquemment, par exemple, pour la détermination de la performance du convertisseur solaire. Il est décrit un procédé rapide permettant de tirer cette caractéristique pour tout niveau de lumière d'une caractéristique correspondante obtenue pour un niveau de lumière différent. Cette méthode fait intervenir deux translations du systéme de coordonnées et n'exige que la connaissance de la résistance en série et de la différence des intensités lumineuses des courants de court-circuits.Une inversion de cette méthode permet de déterminer facilement la résistance en série, en faisant intervenir des mesures à deux niveaux de lumières arbitraires de grandeur non connue.A des niveaux lumineux élevés les effets de la résistance en série se traduisent par un aplatissement de la caractéristique de rendement photovoltaïque et en une chute de la tension du point de puissance maximum. La diminution de rendement résultante doit être neutralisée par réduction des résistances en série pour des applications de cellules solaires avec moyens de concentration optiques, ou bien pour des missions spatiales à proximité du soleil. Dans les parties des cellules, progressivement plus éloignées de la bande de contact, il se produit des tensions de cellules croissantes se rapprochant de l'état de circuit ouvert à des intensités lumineuses très élevées, ce qui donne lieu à une réduction de l'apport de courant provenant de ces parties de cellules et à une déviation de la proportionalité normale entre le courant de court-circuit et l'intensité lumineuse. La mesurabilité directe par la deuxième méthode de la caractéristique de jonction p-n à des densités de courant élevées sans effets de résistance en série met à la disposition de l'ingénieur de mise au point un instrument puissant et, en outre, procure une deuxiéme méthode de détermination de la résistance en série. Les résultats de l'application de cette méthode indiquent que dans la gamme des densités de courants utilisées dans la conversion de l'énergie solaire, la caractéristique des cellules solaires au silicium est décrite par la théorie de la diffusion pour des jonctions n-p avec beaucoup plus de precision qu'on ne l'avait pensé auparavant.
      No preview · Article · Apr 1963 · Advanced Energy Conversion
  • Abdelhalim Zekry added an answer:
    6
    Two solar cells with fixed(different but fixed) voltage and different current are connected in parallel. The parameters of paralleled solar cell?

    The simplest way to obtain the parameters(Voc, Jsc, FF) of paralleled solar cell is by directly adding of two I-V curves. But I wonder is there any expressions I can use to analyse this process, for example, if the short circuit current of these two subcells varied, what will happened to the paralleled Voc?
    I have tried to use the one-diode equivalent circuit equation to link these parameters: Rs1,Rp1,n1,Jph1,J01,Voc1,Jsc1 & Rs2,Rp2,n2,Jph2,J02,Voc2,Jsc2.
    but the expression is far too complicated to use. any advices or recommendation of literatures please?

    Abdelhalim Zekry

    Dear Li

    I want to add to the idea of Jan- Martin but if find my idea is well working i would be be happy if you cite it in your research.

    As an introduction to the idea, i advise you to read thoroughly my comments on the LINK:

    https://www.researchgate.net/post/Solar_cell_parameter_extraction_from_a_single_I-V_curve#view=5716201b5b495284bc42ef06

    The kek of the answer is in my comments there. So based on what has been reached in the comments:

    If two solar cells are connected in parallel then the total current of the combination will be equal to the sums of the two cell currents:

    I= I1 +i2',

    I1= - Isc1 + Id1 + V/Rsh1,

    I2=- Isc2  + Id2 + V/Rsh2,

    where Isc is the short circuit current, Id is the dark current , Rsh is the shunt Resistance and Vis the cell voltage  with the anode at higher potential than the cathode.

    The basic idea is to divide the whole illuminated characteristics into three voltage voltage ranges:

    The voltage range near the short circuit, then only the crosscurrent and the shunt resistance will be dominant and ,

    consequently,

    Isc= Isc1+Isc2,

    and Rsh= the parallel combination of the Rsh1 and Rsh= Rsh1.Rsh2/Rsh1Rsh2,

    Near open circuit, the equivalent circuit of very cell will be dominated by the series resistance and hence  the total series resistance Rs= Rs1 in parallel with Rs2

    = Rs1. Rs2/ (Rs1+rS2 )

    iN the middle voltage range the cell current is dominated by the dark  diode currents which means that the drop on the series resistance is negligible and also the current in the shunting resistances. Consequently

    The total dark current Id= Id1 +Id2= I01 exp V/ n1 Vt + Io2 exp V/ n2Vt =

     I01 exp V/ n1 Vt [ 1+ I02/I01 ( EXP V/ Vt( 1/n2 -1/n1))].

    The last dark current expression can be further simplified according to the relation between the n1 and n2, If n1=n2,

    Then the bold part in the equation will be = I02/I01,

    And the total dar current will be Id = (I01+102) exp V/n Vt= I0 exp V/nVt, where I0 is the total reverse saturation current of the two cells and n is the ideality factor of the two solar cell diodes.

    Wish you success

  • Igor Chernev added an answer:
    17
    What kind of contact materials should I use for back contact a-Si:H solar cell?

    We use the Al  back contact but it's not suitable because Al has very bad adhesion to a-Si:H.

    Igor Chernev

    Dear Abdurashid, Thank you for answer.

  • Sabah Gaznaghi added an answer:
    9
    Which technology do you think will better convert a monochromatic light into electricity than III-V technology (like GaAs solar cells)?

    In other words which technology do you think has better monochromatic conversion efficiency?and why?

    Definitely an optimal bandgap make GaAs solar cells able to better convert a monochromatic light into electricity. But if you have to choose between mono-crystalline silicon solar cells, poly crystalline silicon solar cells and thin film silicon solar cells, which one will you choose?

    Sabah Gaznaghi

    I appreciate your replies. Indeed I am thinking about feasibility of wireless power transport via laser power beaming.

  • Jan-Martin Wagner added an answer:
    4
    The band gap differences of p and n layers in a solar cell?

    https://www.researchgate.net/post/Why_are_silicon_solar_cell_p-layers_is_thicker_than_n-layers

    Quote by Abdulkadir: It is widely known that during the solar cell fabrication n-type material is chosen from large band –gap semiconductor materials (window layer) and p-type material is chosen from lower band–gap semiconductor materials (absorber layer).

    Could someone explain why this is so? I have not been taught about this concept before. Haha because I am taking a course on Photovoltaic Materials and need to clarify my concepts ASAP before taking the exam.

    Jan-Martin Wagner

    A certain part of the quote provides a further correct statement (because it is of general nature): "... large band-gap semiconductor materials (window layer) ...": It is always the window layer that has the largest band-gap, since only then the usage of different band-gap materials as absorber materials makes sense at all.

  • Saeede Tafazoli added an answer:
    5
    Which characteristics make Spiro-OMeTAD the most efficient HTM?

    Every where in the texts, papers, etc.. people talk about what should we do to replace this high-cost hole transport material (Spiro-OMeTAD), but there is nothing about the main reason(reasons) which made it the most efficient HTM. I will be gratefull to know how it get started? because high mobility? high conductivity? low recombination rate? or..?

    Saeede Tafazoli

    Dear Gopal

    I have got my answer, tnx a lot for your complete guide. 

  • Tony Maine added an answer:
    9
    In a multi-junction solar cell, why the total current generated is limited by the low current of sub-junction ?

    multi-junction solar cells

    Tony Maine

    I think that, as Abdelhalim suggests, the term 'tandem cells' should refer to cells which are both optically and electrically in tandem. You could certainly make cells which are optically in series but electrically separate. However, I don't see the point since neither cell is likely to be as efficient as two optimised cells laid side by side. There is some confusion, in my view, as to the need to place cells in series optically; the designers seem to think that they are extracting more power per unit area of cell, and while this is true, one should not forget that the energy source - sunlight - is free and carries no economic or other cost, so the efficiency of extraction is not as important as the overall effectiveness of the array. Certainly, when an energy source carries an economic cost, then it's worth trying hard to get all the energy out of it. If it doesn't carry such a cost, then minimising the capital cost of the array in $ per Pk W is the best strategy. I am far from convinced that placing cells in series either optically or electrically is the best solution  to this, except for very mass-critical arrays as found on spacecraft.

  • Felipe De La Torre added an answer:
    2
    How can I produce a uniform perovskite layer via spin coating on flexible substrates and increase low Isc?

    I am new to the field and need some guidance. I'm attempting on making flexible perovskite solar cells with structure PET/ITO/m-TiO2/CH3NH3PbI3/P3HT/Ag but keep getting low Isc, on average it's below 7E-7 (A) with Voc between 0.15-0.50 (V) which results in <1% efficiency.

    These are the steps that I take to fabricate them:

    1. Etch half of the ITO, followed by ultrasonic bath in acetone and IPA for 10mins.

    2. Apply a TiO2 paste by blade coating or spin coating at 1000rpm for 30s (when spin coating there tends to be a lot of gaps), followed by annealing at 120°C for 1-2hrs on a hot plate.

    3. Preheat TiO2 covered substrate at 70°C and spin coat a 400 mg ml-1 PbI2 in DMF solution (heated at 70°C) at 3000rpm for 30s.

    4. Apply drops of MAI solution on top of the PbI2 layer or submerge substrate in MAI solution for 10-20mins.

    5. Anneal substrate at 90°C for 30-60mins.

    6. Spin coat P3HT at 1000rpm for 30s (1-2 layers).

    7. Sputter Ag on another substrate and place on top of the substrate with the layers.

    Everything is done in air environment where humidity has been ranging from 35-50%.

    I have some other questions that I would appreciate if you could answer.

    1. Is it the pattern of the etching important? If so, how can I determine what pattern is good?

    2. I have attempted sputtering Ag on top of the P3HT layer but get no results, by placing the sputtered Ag substrate on top I am able to get some results. Is it possible to sputter Ag on top of the P3HT or would I need a thermal evaporator? 

    3. After checking some samples in the SEM, I've noticed that the perovskite doesn't make a layer on top of the TiO2 but makes patches of it. Am I applying the PbI2 wrong?

    4. How is the active layer determines? I have made cells that are 2cm x 2cm and put a 0.5cm x 0.5cm mask on top to calculate the efficiency, is this acceptable or does the active area need to be that size?

    Unfortunately we don't have a lot of equipment/material in the lab so I'm very limited to what I can use, but there is also ~3g of PEDOT:PSS and some PCBM in case that could help me in any way. Any help would be greatly appreciated.

    Felipe De La Torre

    Thank you for your reply Mr. Zekry, I will look into it and see if I can get some CHP

  • Umesh Nakate added an answer:
    5
    How different method of nanomaterials synthesis effects on performance in applications e.g photocata lytic activity or gas sensor or solar cell etc?

    why and how different methods has influence for same metals oxide for same applications.. why different out puts?? 

    Umesh Nakate

    thank you to all experts for answering..i am really glad u took time and gave such enlightening guidance. i think i got many factors and reasons and answers. thank you all. have nice time..

    cheers

  • Hammad Cheema added an answer:
    9
    How we can etch and pattern FTO glass with Zinc powder and HCl for perovskite solar cells?

    How we can mask?

    Hammad Cheema

    I would guess it will be on one's own discretion based on the desired pattern. 

  • Subir Maity added an answer:
    1
    How to add a user defined material (AlGaSb) in silvaco programming?

    I want to use AlGaSb as a quntum dot material or tunnel diode material in solar cell simulation?

    Subir Maity

    To create a parameter file of AlGaSb first thing you have to do is collection of physical data such as mobility, band gap, effective mass etc. You can search papers, literatures or handbook of III-V materials by S.Adachi. Also you can see NSM website for physical parameters. Then create ATLAS deck and apply those values in material and model section.Remember that accuray of simulation  depends on accuracy of physical parameters.

  • Tony Maine added an answer:
    5
    How can a load absorbs most of its current from a Grid-tie Inverter?

    I have been reading some papers and articles about grid-tie inverters fed by PV cells and I can not make a clear idea of the following case:

    • Assuming a 220 Vrms single phase grid line.
    • A PV array + inverter capabe to draw 3Kw.
    • A load (for example an air conditioner) that absorbs 3.5Kw
    1. Is it possible that 3 out of the 3.5Kw consumed by the load are provided by the PV system and the 0.5Kw left is provided by the grid? (So the inverter is drawing all of its power capacity)
    2. If yes: how does this happen exactly? (as far as I understood both PV+Inverter and grid side should have same voltage-phase-frequency. So,how can the PV+inverter provide a higher current if the three previously mentioned parameters are the same -and so is the load- ?)

    I am looking for your replies!

    Thank you.

    Tony Maine

    Mauricio, consider what happens if you connect a load to the grid - without any inverter or anything else. Power flows from the grid into the load, and in doing so the grid voltage will drop slightly according to the 'output impedance' of the grid. In most cases it will be a fraction of an ohm; but it will not be zero. Therefore if you now connect an inverter it will try to drive current into the grid thus raising the grid voltage, again slightly, according to how much current it attempts to drive. The power you are considering in your example is split between the grid and the inverter because of the grid output impedance. If this impedance were zero then the split of power between the inverter and the grid would become indeterminate, as you suggest.

  • Sanjoy Roy added an answer:
    8
    Can you please advise me the best tip to identify the maximum power for a solar cell from a set of given voltage and corresponding current?

    I tried to draw a graph but still I am not getting the right power!

    Sanjoy Roy

    Hi Arnaud,

    Sorry for the delay by about a week. I was away from Ropar and had to go over to New Delhi for a few days.

    Anyway ! Now that you have confirmed that the (V, I) value pairs indeed give you steady state operating points, an approximate estimate of maximum power can be obtained as follows:

    1. Plot the (V, I) points using Grapher or MS-XLS or any other plotting software of your choice.
    2. These software have ways of curve-fit into data scatters. Use one of those (I would suggest splines) to plot an approximate steady state output characteristic. It need not connect all your points, but should be a "best-fit".
    3. Locate the point on the plot that is called a knee point. This is where the voltage seems to drop sharply with very little increase in current. The knee point occurs on your "best-fit" curve but need not be physically identical to any specific experimental point.
    4. Read the voltage and current at the knee point of the "best-fit" curve that you plotted.
    5. The product of this voltage and current (from #4) is an estimate of the maximum output power.

    Cheers !

    -Sanjay

  • Yoosuf Ameen M added an answer:
    8
    In a solar cell if series resistance increase by a certain amount, how much should the shunt resistance increase for the current to remain same?

    I = Iph − I0[exp {q(V+IRs)/nkBT}-1] − (V+IRs)/Rsh

    Yoosuf Ameen M

    Thank you.

  • Thomas Stergiopoulos added an answer:
    8
    Why is the open-circuit voltage in a PV cell less than the bandgap voltage of the PV material?

    Why is the open-circuit voltage in a PV cell less than the bandgap voltage of the PV material?

    In other words, what is the physical interpretation of the voltage factor in a PV material? In which: VF = V_oc / (E_g/q).

    Any detailed physical explanation would be highly appreciated.

    Thomas Stergiopoulos

    after I agree with what's writen above, I will try to provide also my explaination in a more simple way ( I hope so!). As a start for my arguments I will state that I am worried only about the material which absorbs light (absorber), being a semiconductor with a defined bandgap, and I am not referring to (any kind of) junctions which help to separate charges and drive them selectively towards the electrodes. This is another story, most of the times, the built-in voltage at the junction drives charge separation and thus limits Voc. But again, in my opinion, this has nothing to do with Eg of the absorber. So here I briefly present two things: 1) thermodynamically, a solar cell is an energy converter: from solar to electricity. The solar energy is what the system receives, in the case of a semiconductor a photon of adequate energy is absorbed by a valence electron, gaining kinetic energy to move to the conduction band (if the energy is higher than bandgap, we dont care, the electron will thermalize at the conduction band edge anyway- unless it is hot). Thus, the maximum energy that the system can convert (otherwise stated free Gibbs energy) is obviously that of the bandgap: the electron will arrive at the electrode with this energy (neglecting EVERY energy limitation such as recombination). It cannot arrive with a higher energy, it is thermodynamically impossible! 2) As Dr. Md. Muhibbullah states above, the origin of the photovoltaic effect is the Fermi level splitting. The higher the splitting, the higher the Voc. In a semiconductor, the maximum splitting of Fermi levels OBVIOUSLY happens when EFn attaches Ec and, simultaneously, EFp attaches Ev, thus BANDGAP.         

  • Upendra Tagare asked a question:
    Open
    Does any one have a model of solar cell in PSCAD??

    Plz provide a model of PV Cell in PSCAD.

  • Hong ZHANG added an answer:
    4
    What's the order of the coordination between Pbi2 and DMSO, DMF, and GBL?

    I am researching the relationship between perovskite morphology and the coordination between PbI2 and solvents such as DMSO, DMF, and GBL. The rough data showed that there existed some phenomena related with the coordination.  Can you provide any  published papers on the coordination between PbI2 and  DMSO, DMF, and GBL?

    Hong ZHANG

    I also use endnote and classify the papers into different groups. So that you can find out what related papers quickly.

    Hong

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