Solar Cells

Solar Cells

  • Geetak Gupta added an answer:
    What is the use of barrier layer in solar cells?

    GaN/InGaN heterostructures with AlGaN barrier layer

    Geetak Gupta

    During normal solar cell operation, light generated electrons move towards the n-type layer and holes move towards the p-type layer. This results in a build up of a potential difference. Due to this potential build-up, it can become easier for the light generated electrons to diffuse towards the p-side instead of the n-side. This is undesirable as it reduces the potential build-up and hence efficiency.

    Insertion of a barrier layer like AlGaN can be used to reduce the diffusion of light generated electrons into the p layer and thus increase efficiency.

  • Ariadne Tsambani added an answer:
    How to create a material file in PC1D for solar cell simulation?

    Iam working multijunction solar cell using PC1D. Iam not knowing to add material other than in library.

    Ariadne Tsambani

    Good Evening. Please find attach the link

    .Regards Ariadne Tsambali

  • Anika Amin added an answer:
    How can I extract the absorption coeficient curve of a Quantum Dots/Wells solar cell in silvaco?

    Im looking to find a way to extract the absorption coeficient curve using silvaco of QWSCs or QDSCs 

    Anika Amin

    thanks a lot! :)

  • Ariadne Tsambani added an answer:
    In forming a CZTS absorber layer for solar cells, how could I manage to get the cu/(Zn+Sn) ratio as 0.9 by non vacuum technique?

    CZTS absorber for solar cells In forming a CZTS absorber layer for solar cells, how could I manage to get the cu/(Zn+Sn) ratio as 0.9 by non vacuum technique?

    Ariadne Tsambani

    Good Evening. Please find attach the link

    .Regards Ariadne Tsambali

  • Ralf Meyerhof added an answer:
    Please does anyone have any material on "auto cleaning of solar panels"?

    By cleaning,I mean removal of dust particles from the solar panels for maximum light intensity

    Ralf Meyerhof

    @ Kennedy: It all depends on the individual conditions. Dry arid region with high wind and swirling dust? Rain in certain seasons? Availability of water? Availability of labor? Requirements / restrictions of the module manufacturer (warranty conditions)?

    You might Goole "modul reinigung" but it´s all German. Haven´t checked "module cleaning". We have a long experience with cleaning options. With rain at least every few weeks we see energy losses of 1-2% with no cleaning at a tilt angle of ~25°.

    @ Markus: I would not recommend any electric field system on a PV module. It might disturb the operation with such high voltage and frequencies or even damage the module.

    @ Vladimir: Please no robots like that. It will destroy the back sheet. Only front side cleaning. If wet cleaning only use purified water.

    Water consumption with semi robots is about 1 liter per m² and capacity about 2-3MWp per day. Most systems are with brushes and some with compressed air and some can do dry as well as wet cleaning. The attached document is unfortunately only in German but it gives some impressions and links.

    My recommended approach: first measure the shading effect on a single module or string over some time depending on your conditions for days, weeks or month. Then calculate the loss and then decide about the investment.

    Good luck
    Ralf (Cape Town, SA)

  • Tony Maine added an answer:
    What can be the possible ways of increasing efficiency of solar cells using graphene?

    Graphene having excellent properties can be utiized for solar cells and thus efficiency of a solar cell can be increased.

    Tony Maine

    Sadly I don't know of any solar cell technology either in use or under development that is going to substantially undercut the cost of silicon, for two reasons. The investment required will be at least as much as has been put into silicon - maybe a billion US$ over 40 years, and secondly because the photoactive layer is now such a small part of a solar panel making it cheaper will not have a strong effect on the cost of the panel. I am not saying that we shouldn't do it, but be aware of what you're up against in silicon! It will not be easy to replace it on a large scale. Maybe perovskite cells integrated into the roof structure (Building integrated PV) will do the job. We just don't know.

  • Yasser E Abueldahab added an answer:
    How to tune and implement PI controller in solar PV standalone system?

    Tuning method, input parameters, block diagram etc. like this

    Yasser E Abueldahab

    simply , there is a reference voltage , and generating a switching pulses based on (Vout - Vref ) in order to tune the Vpv to be at the maximum power point.

    see  pi control in this publication

    • Source
      [Show abstract] [Hide abstract]
      ABSTRACT: The development of maximum power point tracking (MPPT) is continuing in order to increase the energy transfer efficiency of the solar photovoltaic system. This paper provides a review of the conventional maximum power point tracking techniques that is enhanced by the presentation of a new technique. The new method is based on a genetic neural algorithm in order to predict the closest point to the maximum power point (MPP), which will be the kickoff point of the search process. Not only does the new technique start the search process from the nearest point to the MPP, but also the developed search algorithm is very fast. Consequently, the time taken to reach the MPP is reduced. In order to determine the new MPPT performance, a complete photovoltaic generator system is modeled and simulated using the MATLAB/SIMULINK package. Simulation results show that the new technique reaches the MPP in less than 100 sample times compared to tens of thousands of samples for conventional methods. Furthermore, the new technique reaches directly the target MPP with small deviation from the intended values. Consequently, the new technique has a significant improvement in energy extraction efficiency from the photovoltaic array to the load, in addition to higher tracking speed and system stability compared to the conventional ones.
      Full-text · Article · Dec 2014 · Renewable and Sustainable Energy Reviews
  • Sadia Sultana added an answer:
    What would be the ideality factor of a Gallium Nitride based solar cell diode?

    I am trying to simulate Gallium Nitride based pin solar cell with Indium Gallium Nitride quantum dots ambedded in the intrinsic region. Can anyone help me with supporting resources?

    Sadia Sultana

    That's very nice of you... I had download the software at earlier stage of my work, but the problem is, the licence/crack doesn't work....that is why I am doing the job using analytical model... :(

  • Martin Stutzmann added an answer:
    How do I analyze defect in Si-solar cell with Raman Spectroscopy?

    Can anyone provide me a good article on how to use Raman spectroscopy? I want to know how I can use Roman spectroscopy to detect defect in PV solar cell

    Martin Stutzmann

    You should be careful with this. Raman spectroscopy in most cases will give you only information about structural defects (impurities, strain, grain boundaries etc.) More relevant for solar cell performance are electronic defect states already at small concentrations, and there is no reliable quantitative link between structural defects and electronic defects.

  • Peter Mathew added an answer:
    How can I fabricate MIS solar cell in lab?

    The solar cell that we are trying to fabricate is similar to the proposed cell in the paper which was Au/NiO/c-Si/TiO2/Al. Attached is the paper as well. 

    Previous in-lab fabrication efforts include testing the following cells:

    - Au/NiO/c-Si/Al

    - Au/c-Si/TiO2/Al

    - Au/NiO/c-Si/TiO2/Al

    - Au/c-Si/Al

    each of the above gives same iv curves in dark and when light falling on the surface..

    The oxide layers were grown using sputtering with thickness ranging from 13-20nm . contact were also sputtered in the same way. c-Si(n-type) was around 300um. When each of the above cell was measured for iv curves, they gave diode like curves in dark (as expected), but the issue is, in UV light they are giving the same curves which essentially means the cell is not generating any current.

    Not knowing where we are lagging, we tried different approaches. like testing the cell with only one oxide layer (with a hole or electron blocking layer), testing both simultaneously, or including no oxide layer as in the last one, with just a thin layer of gold on one side of c-Si and Al as contact on the other side. In theory, this is also a solar cell but this does not work as well. 

    Please suggest some method  or any advice on how to grow thin oxides on c-Si for MIS solar cell

    Peter Mathew

    Sputtering is more viable for deposition of Au and Al. You may also try using PVD for Al.

    However for deposition of metal oxides, particularly the materials of your interest PLD and MBE would give you fine results.

  • Federico Brivio added an answer:
    Can anyone please inform me the roles of different layers used in Perovskite Solar Cell? I want to know the details mechanism. ???

    Please share the details mechanism of the different layers used in Perovskite Solar cell e.g, FTO, TiO2, Perovskite layer, hole transporting layer, Ag/Au.

    Thank you.

    Federico Brivio

    Simple description of Perovskite Solar cell e.g,
    FTO  = conductive transparent substrate
    TiO2 = Semiconductor where the perovskite is deposited. This create a mesoporous interface, where electron are injected.
    Al2O3 = Substituted TiO2  in some cell, in this case, the electron can not be injected, and it acts as a simple support for the perovskite.
    Perovskite layer = adsorb the light and create the e-h couple. The electron can be injected in the inorganic support (TiO2 or Al2O3) or transported. Same for holes, that are usually injected in an inorganic transport layer (as CuI) or in an organic one
    hole transporting layer = it covers the perovskite and collects the hole. Can be organic usually or inorganic.
    Ag/Au = back contact

  • Ramasamy Murugesan asked a question:
    What might be the reason for low Isc in P3HT:PCBM Organic soalr cells?

    I am trying to make BHJ solar cells. I am getting considerable Voc of 0.4 to 0.5 V. But Jsc is very low in the range of microamps. what might be the reason for it.

  • Abdelhalim Zekry added an answer:
    How to calculate bandgap alignment for different layers used in Perovskite solar cell??

    I do want to know the procedure of the bandgap calculation and the drawing software. Is this draw manually?

    + 1 more attachment

    Abdelhalim Zekry

    The energy band alignment is dictated by the function of the layers in the solar cell. It is so that the absober material say the perovskite must have an energy gap corresponding to the maximum conversion efficiency of about 1.35 eV. Then one has to add on one side an electron transport layer ETL whose conduction band edge Ec slightlylower than the conduction band edge of the absorber while at the same time its valence band edge is lower than that of the absorber to reflect the holes and prevent them flowing in the ETL. At the other side of the absorber there exist a hole transport layer HTL with the valence band edge is slightly above that of the absrber to facilitate the flow of the holes in its direction while its conduction band edge lies above that of the aborber to reject the electrons and prevent them from flowing in the HTL.The metal electrode adjacent the ETL must have fermilevel below that of the ETL. The metal electrode contacting the HTL must have fermilevel above that of the HTL.

    After selecting the appropriate materials , there are two methods to align the bands. They can be drawn with respect to a reference level called the vacuum level. This is the alignment before contacting the materials. After contacting the materials they are aligned by the Fermi level. Under thermal equilibrium the fermilevel will be a horizontal line through out the structure. The fermi levels is that level with equal probability of electrons and holes. Intrinsic semiconductors have their Fermi level in the middle of the energy gap. The fermi level shifts towards the bands if the materiel is doped. The fermi level of the metal lies under the vacuum level with the work function of the material. The conduction band edge of a semiconductor material lies under the vacuum level by the electron affinity.

    Knowing these information one can easily draw the energy band diagram of the whole structure. It is a simple diagram and can be drawn easily by any drawing program or manually.

  • Shahzada Qamar Hussain added an answer:
    Is it possible to have very high (~100)% haze ratio of the wet chemical textured Glass substrates?

    Dear All,

    I have been working on various light trapping techniques for the a-Si thin film solar cells.

    Recently, I came across a case of wet chemical textured Glass (high etching depth:>5 um, hazy surface) substrate.

    When we measured the optical transmittance (Total, Parallel, Diffused) of samples by the equipment (Haze Master-Scinco). We see that the samples with high etching depth and hazy surface showed almost similar total and diffused transmittance. i.e Haze ratio: ~100. Is it possible for a sample to have 100% haze ratio...? I am surprised of it....Can any expert please guide me...

    In several research paper like from Konagai et. al and few other they used index matching solution to measure the optical (TT,DT) properties of such samples...We also used the index matching (CH2I2, n=1.74) solution in several case....But those results are different from the normal results without index matching solution...Can anyone please guide...which method is better...



    Shahzada Qamar Hussain

    Thanks a lot Sven Ring for useful information...

    The applications is a-Si thin film solar cell (single junction and tandem)..

    We are already very much caring about the feature size, etching depth, roughness, TT and Haze ratio. 

    Also We understand textured glass with high etching depth and large feature size are difficult to be used for high efficiency of a-Si thin film solar cells.

  • Luis Arce-Plevnik added an answer:
    Calculation the volume of CH3NH2 and HI/HCl for the solat cell preparation?

    how do calculate the amount the CH3NH2 and HI/HCl acid for perovskite solar cell preparation.

    I have 33wt% CH3NH2 and 57wt% Hi/37wt% HCl.

    Please give me the formulation.

    Luis Arce-Plevnik

    Basically, you are talking about the synthesis of organometal perovskite sintezisers.

    You may take a look into a supplementary paper by Yang et. al (2013) which appears under The Royal Society of Chemistry, that deepens on this matter. Let's have 0.3 mol (38 mL) of CH3NH2 solution (33wt% in absolute ethanol) - reacted with equimolar (40 mL) of HI (57wt% in water). Stir at 0°C for couple of hours in order to syntesize the methylammonium iodide (CH3NH3I).

    Thus, the crystalization of the CH3NH3I can be obtained through a rotary evaporator at 60°C for no more than three hours.

    For further clarification, you can read the paper I have quoted.

    Regards, Luis Arce-Plevnik, BSc. Eng | MICD.

  • Santo Martinuzzi added an answer:
    What is the best green semiconducting photovoltaic material to use in a solar cell?

    Toxic waste management is a big problem, people do not dispose of old solar cells properly which leads to pollution, which is the most efficient or cheapest(reasonable efficiency) and green semiconducting material for use in photovoltaic solar cells?

    Santo Martinuzzi

    The semiconducting absorber for PV cells must be very abundant, non toxic and stable for 30 years, at least. In addition it  must be as less expansive as possible. Today there is only one candidate: SILICON (crystalline, multicrystalline, polycrystalline or amorphous). 

  • Tony Maine added an answer:
    Why is the Jsc of tandem solar cells are typically lower than Jsc of the subcell that produces lower current?

    I have read several papers about (organic) tandem solar cells, in some papers Jsc of tandem cell is almost equal to Jsc of the subcell that produces lower current and in some of papers Jsc of the tandem cell is lower. Which parameters cause lowering the Jsc of the tandem cell compared to the Jsc of subcell with lower current?

    Tony Maine

    Farhana, consider what would happen if both cells were identical and both designed to work as well as possible with the incident solar spectrum. Now change one cell - by definition, you have made things worse because  both the first cells were optimum and now  one isn't. But this doesn't solve the same problem as the tandem cell is designed to solve. The tandem cell is designed to extract as much power as possible from unit incident irradiation. This is exactly the right approach when making two cells in tandem results in a lower mass structure, essential for a spacecraft. On the earth's surface it is rather different. Highly efficient conversion of solar energy is desirable when the energy supplied has a cost. But sunlight doesn't have a cost - it's free, so designing a cell to extract more power may not (in practice, won't) be a better economic solution than just making your array a bit bigger.

    The cost of doubling the size of a ground based array is probably  slightly less than 2. The cost of using tandem cells instead of silicon might increase the cost 50 or 100 times. It isn't worth it!

  • Mohammad Abu Raihan Miah added an answer:
    What are complex transmission and reflection coefficients and How can we determine them between any two layers ?

    How can we determine Fresnel complex transmission and reflection coefficients between any two layers. For example the transmission and reflection coefficients between AlGaAs and GaAs layers of solar cells.

    Mohammad Abu Raihan Miah

    You can use transfer Matrix theory to calculate that. You can follow the approach from the following paper.

  • Anand Selvin Subbiah added an answer:
    why does the spiro-ometad solution with LiTFSI and tert-butyl pyridine turn red in colour with time and stirring?

    Spiro OMeTAD solution made for Perovskite solar cells are turning red in color when taken inside a glove box or when they are stirred excessively. Can anyone please let me know the mechanism involved?

    Anand Selvin Subbiah

    Thanks so much giles. And yeah i goes deep red in dry box and Glove box slightly pinkish probably since the lithium TFSI was stored in ambient for  a while. I saw the study recently, made by Prof. snaith on this probably published in 2009  i guess.

    Thank you so much once again. Will make sure to make necessary storage conditions.

  • Abdelhalim Zekry added an answer:
    How to find electron life time values from open circuit voltage decay values using equation?

    I want to find electron lifetime from the open circuit voltage decay measurement using equation.

    The equation is: Electron life time= -[(KBT)/e]*(dVoc/dt)^(-1)

    where KB is the Boltzmann constant, T is the absolute temperature, e is the positive elementary charge, and t is the time interval of the OCVD measurement.

    Below I have attached the Voc values. How to convert from Voc values to life time?

    Abdelhalim Zekry

    The open circuit voltage decay with time is a conventional method to measure the life time of the minority carriers in the base of the pn junction diodes.

    It is so that the stored charges decay exponentially with time because of recombination.

    It is so the excess charges decay exponentially with time such that 

    delta p = delta p(0) exp -t/ Tau , where Tau is the lifetime and delta p (0) is the intial excess hole concentration at zero time, the instant of interrupting the diode current after forward bias.

    On the other side according to the law OF THE JUNCTION:

    delta p = Pno exp V/ Vt, where Pno is the minority carrier concatenation at thermal equilibrium and Vt the thermal voltage.,

    equating both equations one gets:

    V/Vt= V(0)/Vt - t/Tau,

    Differentiating the above relation, we get finally; 

    delta V/ delta t = Vt / Tau.,

    If the diode has an ideality factor n, one has to modify the above equation to:

    delta V/ delta t = n Vt / Tau.,

    To get the lifetime you have to display V(t) as a function of time and evaluate the slope of the curve at the larger values V where the effect of the space chrge junction capacitance is negligible. This has been noticed by Johannes.

    wish you success.

  • Varun Vohra added an answer:
    How much important is the purity of zinc precursor for solar cells by sol-gel process?

    I'm using zinc acetate dihydrate (98-101%, alfa aesar) for zinc precursor. 1g Zn(CH3COO)2 · 2H2O was dissolved in 10 mL 2-methoxy ethanol and 0,275 mL MEA was added into solution. The solution was stirring 2 hours at 60 °C and it was rested for a one day. End of the one day, the sol was filtred by 0,22 µm filter. Obtained sol was coated onto ITO with different rpm's by spin coater. By the way the structure of solar cell is ITO/ZnO/P3HT:PCBM/MoO3/Ag. However I can't reach above 0,8% efficiency. Is there any relation with zinc precursor purity and efficiency. Is it really important a little differences  ( eg. from 98% to 99,5%) inpurity of zinc acetate dihydrate.

    Varun Vohra

    Dear Semih,

    In our work (see Nature Photonics paper on my profile or link below), we were able to obtain PCE upto 10.1% using a similar approach with a zinc acetate dihydrate purity 98% or above from Wako. This was not with P3HT:PCBM of course.

    What are your annealing conditions for the ZnO layer? and do you know the approximate thickness of your ZnO films?

    Just to make sure that the problem doesn't come from somewhere else, what kind of efficiencies do you usually get when you fabricate (for example) P3HT:PCBM regular architectures?

    If I may suggest one thing as well, be very careful when depositing the MoO3 layer on top of the active layer. If the MoO3 diffuses into the active layer (evaporated too fast) the devices don't usually work very well.

    If you could provide the other parameters and details for your device fabrication, I might be able to help a bit more.


  • Closed account added an answer:
    Is there an efficient way to calculate the Rs and Rsh of the( module )Solar cell?

    I'm doing modeling of photovoltaic cell (module )and looking for a way to calculate the Rs and Rsh of the module?


    Dear Tony,Thank you for your reply,  I need this  for a real model, tso the method that  Prof.Zekry mentioned has mentioned  that what I will use.

    Thanks for everyone


  • Ahmed S. Jbara added an answer:
    Trying to develop a solar cell model on COMSOL Multiphysics 4.3a
    We are currently working on the attached model of a simple pn solar cell with COMSOL Multiphysics 4.3a. The model has been adapted from the old 3.5a COMSOL semiconductor diode tutorial, which is available here: Unfortunately, whenever I change something in the model, the computation does not converge. For example, if I set the generation and recombination terms to zero, the model does not converge. Another issue is that I am getting absurd values for the current density. Unfortunately COMSOL support is not helpful at all, despite the fact that we purchased a $ 8.5k license. This model currently employs the following modules: AC/DC and Chemical Reaction. The model hasn't been coupled with the RF module yet, via the generation term. Maybe this way of implementing a model of a solar cell is not good. Do you know the best way for implementing the drift-diffusion model for a simple pn solar cell? I was thinking about three options: 1) (Implementation via the Plasma Module (which we don't have ... :-( )); 2) Rather than using the continuity equation in the convection and diffusion nodes, where the variables are nc and pc but also the Lagrange Multipliers nc_lm and pc_lm, probably we should use a different formulation where the variables are the IMREF Efn and Efp. This was described in Malm et al., 2009, Solar Energy Materials & Solar Cells doi:10.1016/j.solmat.2008.11.058 . The authors report that <>. But how do we implement that on comsol multiphysics? 3) Maybe we should use the Equation Based modeling... how do we implement that on comsol? The objective on the final modeling is to build a solar cell model of a micromorph solar cell, which we will optimize via Matlab Livelink by using the Genetic Algorithm toolbox.
    Ahmed S. Jbara

    Dear Samuele Lilliu, this comsol model not work.

  • Sri Harsha Pavuluri added an answer:
    Has anyone ever done modeling and simulation of electrostatic discharge on a solar cell?
    Need to introduce a software package for modeling and simulation of electrostatic discharge on solar cells satellite. Rate of change in array power and voltage.
    Sri Harsha Pavuluri

    I suppose you can use Synopsys Saber for this purpose.

  • Bulkesh Siwach added an answer:
    What characterizations are important for the support of counter electrode of DSSC basically?

    i have made graphene counter for DSSC application and want to know the minimum characterizations in this regard.

    Bulkesh Siwach

    Thank you Sir. I will.

  • Mohammad-Reza Ahmadian-Yazdi added an answer:
    Which one is suitable or better for use in perovskite solar cell? PEDOT:PSS PH 1000 or PEDOT: PSS AL 4038?

    i am using PEDOT:PSS in my perovskite solar cell but i don't know which one of  following products has better conductivity as a hole transfer layer.

    PEDOT:PSS PH 1000 or PEDOT: PSS AL 4038 ?

    Mohammad-Reza Ahmadian-Yazdi

    You can use both but  the work function is different

  • Swaminathan Venkatesan added an answer:
    How do I plot the trap density of states for perovskite solar cells using C-f and C-V Data?

    I have done both C-f and C-V measurements at room temperature (300 K) for my devices. However I am not sure on how to estimate the trap density of states (tDoS) since I am not sure of the dielectric constant and attempt to escape frequency. I see some papers have plotted the tDoS by this technique (e.g. doi:10.1038/ncomms6784). However there is no mention on how these two parameters were estimated. I want to compare two different devices where the active layers processed under different conditions. Will the dielectric constant and attempt to escape frequency be the same for the two. Is it possible and right to estimate tDoS without performing C-f measurements at different temperatures?

    Swaminathan Venkatesan

    Thanks Dr. Zhou for your answer and help. Some authors have calculated the tDOS without using temperature  dependent capacitance measurements as I have stated this in question. I am not sure if it is right to calculate tDoS without doing temperature dependent C-F. Secondly as the authors of that paper (doi:10.1038/ncomms6784) do not mention, I believe they has assumed attempt to escape frequency value. 

    If I have two devices with the same material processed in two different ways, will the attempt to escape frequency be the same? Will it not change based on the capture cross section? In such a case, is it not wrong to assume the value?

    I am not sure how these papers get accepted in Nature when either the authors intentionally miss giving information or perform wrong calculations based on certain assumptions

  • Samuel Tesema Lakew added an answer:
    Are there territories that utilise solar renewable energy sources as the only (or majority) solution for provisioning electricity to their publics ?

    The sustainability of planet earth is dependent on the harmonious co-existence of human-kind with the earth.  An electricity solution built on consumption of fossil fuels and other non-renewables, is a depletion model which is not sustainable.  Are there many jurisdictions around the globe that are harnessing solar renewables in a robust way ?   Which are the most notable of these ?  

    Samuel Tesema Lakew

    Portugal has such a large scale photovoltaic installation in Serpa, 200km southeast of Lisbon. The 11MW solar power plant uses 52,000 hotovoltaic modules and cost around $75m. 

    Here is also the no. one largest photo-voltaic farm in the world. Solar Energy Generating Systems is currently the largest operational solar power plant in the world. It is located in the Mojave Desert of California, US. It has an installed capacity of 354MW and generates 662GWh of power annually. You can see how huge this is from the picture.

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