Solar Cells

Solar Cells

  • Nauman Khan asked a question:
    Life Cycle Assessment (LCA) of solar Cell.

    How the life cycle assessment of solar cell can be carried out?

  • Arnulf Jäger-Waldau added an answer:
    MPPT methods?

    Hi, Does anyone have a new idea on MPPT for solar cells?

    Arnulf Jäger-Waldau · European Commission - Joint Research Centre

    Have a look at

    Advance in Electronic and Electric Engineering.

    ISSN 2231-1297, Volume 4, Number 3 (2014), pp. 285-296

    © Research India Publications


    International Journal of PhotoenergyVolume 2010 (2010), Article ID
    245316, 11 pages
    Review Article

    Recent Developments in Maximum Power Point Tracking Technologies for Photovoltaic Systems


    Particle Swarm Optimization Based MPPT for PV System under Partial Shading Conditions

  • Robert Karsthof added an answer:
    Can I calculate the quasi Fermi levels in a p-n junction solar cell in the case of the absorption of a single photon?

    We know that the "driving force" that separates photo-generated charge carriers in a solar cell is not merely the built-in potential of the junction, but the gradient of the electrochemical potential which takes into account both electrostatic potential and concentration gradient of charge carriers.

    If we consider now the absorption of a single photon within the space charge region of a solar cell p-n junction, this locally creates a small increase of charge carrier concentrations and thereby also a splitting of the quasi Fermi energies (=electrochemical potentials, Fn,p) of electrons and holes. Is it possible to draw the quasi Fermi levels, for example under short-circuit conditions?

    My problem is that I do not understand how a separation of the e-h pair can happen when considering the electrochemical potentials. I am aware that, since the excitation takes place within the built-in electric field of the junction, the carriers will drift into their respective majority regions. But from the electrochemical point of view, there should only appear a "delta-like" peak in Fn and Fp, and since there is no gradient of the quasi Fermi levels, no directed current can result..

    Robert Karsthof · University of Leipzig

    Dear Manuel,

    thank you for your answer. Actually, I've been reading Würfel's book, and his remarks on the working principle of the solar cell made me think about this. But maybe I will find something on this subject when I keep reading....

    The cells I work with are not 'standard' Si cells, but UV-active cells where absorption takes place mostly in the depleted region of the absorber. That is why I am so interested in the mechanism that, based on Würfel's thermodynamic arguments, leads to charge carrier separation. But I guess these arguments can only be applied in the case of a large amount of photo-generated carriers...?

  • Torsten Oekermann added an answer:
    Why do solar cells have a negative short circuit current (Isc)?

    The I-V characteristics of solar cell show a negative short circuit current. Is this negative value because of minority charge carriers or not. Is it possible to explain the working of solar cell as p-n junction diode.

    Torsten Oekermann · Friemann & Wolf Batterietechnik GmbH

    Essentially, a solar cell is a diode. In the dark, any diode will show a negative current when a negative voltrage is applied and a positive current when a positve voltage is applied. By convention (see Shockley equation) the positive side is "forward bias", where we see the flow of majority carriers and therefore the exponential current increase.

    As a consequence, since the photocurrent is caused by photogenerated minority carriers, it has a negative sign. Also note that, in the so-called "power quadrant" where you can draw power from the solar cell, current flow and APPLIED (outer) voltage indeed have opposite signs. It has to be this way, otherwise you could not draw power from the solar cell !

    However, in solar cell research, the current is usually plotted vs. the OUTPUT voltage of the solar cell, so that current and voltage have the same sign. In this case, there is no reason to stick to the sign convention of the diode characteristic, so both are usually given positive signs.

  • Everett E. Crisman added an answer:
    How do you determine the voltage sweep sign to obtain the I-V curve for a solar cell?

    Hi, I am trying to obtain the I-V curve of a semiconductor using Gamry 600 potentiostate to get Isc and Voc. My cell set up includes ITO/TiO2 (or my modified semiconductor)/electrolyte/Pt where Pt is the counter electrode and TiO2 (or my testing semiconductor) is the working electrode. Now, I am a bit confused what applied voltage I should run. Should it be from 0 to 1V (positive or reverse bias) or from -1V to 0V (negative or forward bias)? In literature, I found the I-V graphs can be both.

    Everett E. Crisman · University of Rhode Island

    Let me first point out that semiconductors have I-V characteristics exactly like those of resistors; i.e. straight lines.   I'm assuming from your description that you actually want the I-V characteristic of a semiconductor PN junction or semiconductor-metal junction. In either case there is probably  enough information above to tell you how to get what you need but I'll add an unambiguous check you can do.

    In un-illuminated conditions, run a complete diode I-V junction characteristic using any semiconductor device analysis tester, O-scope with suitable plug-in or  other  basic device characterization electronics you might have access to.  I assume you will be able to distinguish the forward and reverse portions of the trace from that or else the junction is not  very good as either a diode or as a PV device.

    Repeat now with whatever illumination you are using.   The section of the trace that has the information you are seeking lies in the fourth  quadrant of the forward biased section of the device trace between V=0 and I=0. (the lower left quadrant in a traditional diode characteristic.)   In typical PV device reporting the 4th quadrant is usually separately and inverted to show what one sees in most books and articles.

  • Alessio Bosio added an answer:
    How to avoid pin holes in molybdenum thin films?

    I am depositing molybdenum on soda lime glass to be used as back contact for solar cell(CZTS) application using sputtering (magnetron). I have deposited ~500nm film at various temperatures and pressures. The problem regarding to resistivity and adhesion is solved but I am not able to get rid of pinholes. What impact it makes on cell performance? If it is permissible then in how much percentage?

    Can anyone suggest me any option or technique to get rid of the problem.

    Alessio Bosio · Università degli studi di Parma

    I usually deposit Molybdenum by d.c. magnetron sputtering in a bi-layer configuration at room temperature. The first Mo film is quite thin, being only 30 nm thick and it is deposited in an Ar flow of 45 sccm, which corresponds to a pressure of 4.5 x 10-1 Pa. The Ar flow is then decreased to 15 sccm, which corresponds to a pressure of 1.5 x 10-1 Pa and a Mo film, approximately 500 nm thick, is deposited. A bi-layer deposition is needed in order to enhance the adhesion of the Mo film to the substrate and to avoid morphological defects on the surface of the film; in fact, the second layer is very compact and dense with a good surface smoothness without pits and pinholes.

  • Alaa J Mahrath added an answer:
    Is 5,6-difluorobenzo[c][1,2,5]thiadiazole UV active?

    Is 5,6-difluorobenzo[c][1,2,5]thiadiazole UV active? If not which charring solution is suitable for its TLC detection? and also please if knows give me information about its stability like air sensitivity etc

    Alaa J Mahrath · University of Babylon

    Dear Baria , I know MSDS about 4,6-Difluorobenzo[c][1,2,5]thiadiazole not 5,6-difluorobenzo[c][1,2,5]thiadiazole and it's consider UV active .and this compound is look like your except the F position.please see this link:

  • Hidayath Ulla added an answer:
    Which kind of Lithium Fluoride is commonly used to fabricate contact of organic solar cells?

    There are five kinds of Lithium Fluoride provided by Sigma-Aldrich, anyone knows which one is most commonly used to be constructed to make contact of organic solar cells ? Since the Lithium-Fluoride interface attach can enhance the efficiency performance of the solar cells. Thank you!

    Hidayath Ulla · National Institute of Technology Karnataka

    I agree with  @Alagar Ramar. Lithium fluoride, Precipitated, 99.995% is the best option.

    We are using the same for organic LEDs.

  • Lukas Strizik added an answer:
    Which is the best method or technique to determine bandgap of material?

    I am developing CZTS(Cu2ZnSnS4) (kesterite)(for solar cell application) thin films by sputtering. I wanted to know the most convenient and reliable method to determine bandgap of the material.

    Thank you.

  • Pushpendra Singh asked a question:
    What is rapid charge separation

    i want to ask what is rapid charge separation and how large dipole moment associated with ? specially in case of solar cell

  • Sai-Anand Gopalan added an answer:
    Are there any alternative storage (other than glove box) for photoactive materials (OPV)?

    Can some one suggest alternative storage place for photoactive materials like P3HT, PCBM, etc. We dont have sophiscated glove-box environment for storage and solar cell fabrication. It is known solar cell processed inside glove box show drastic improvement in photovoltaic characteristics and power conversion conversion than in open-air conditions. How about keeping active materials inside desiccator under vacuum conditions? Please suggest any alternative storage place.

    Sai-Anand Gopalan · Kyungpook National University

    Dear Omar, thank you for the response :)

  • Marius Loch asked a question:
    How do I prepare the TiO2 interlayer for tandem solar cells?

     What precursor do I use for this layers and how can the high temperature step be avoided?

  • Hima Kavuri added an answer:
    Can I use a photo-mask for solar cells?

    What could the possible patterns and the materials used for photo-masks be in the case of photovoltaic applications to fabricate patterned, non-reflective solar cells? Is it feasible to use in a magneto sputtering technique while evaporating metal electrode?

    Hima Kavuri · University of Auckland

    Hi Rafael, 

    Thank you. This could explain one of the reasons for low efficiency in our OPV devices.

  • Chang-Qi Ma added an answer:
    Causes for low Jsc observed on perovskite solar cells

    Did any one experience low Jsc (typically below 10 mA/cm2) on perovskite solar cells while the other two parameters are normal, i.e. Voc around 1 V and FF above 70%? The film thickness and absorption should be sufficient to generate much higher current. The dark current also shows low leakage current. I wonder what causes the low Jsc and how we can improve it.

    Chang-Qi Ma · Suzhou Institute of Nano-Tech and Nano-Bonics, CAS

    Dear Kuan,

    I would follow Paul's suggestion. Please check EQE of your cells, make sure your cells have correct light absorption range. Optical band gap might be different to other perovskite material.

    best regards,


  • Nanette Veilleux added an answer:
    How can I apply silver nanoparticles onto a solar cell?
    How to apply AgNP onto dye sensitive solar cell or thin film solar cell? I have been doing background research on this. Most articles told me it's thermo evaporation. But they don't specified how. Any help is appreciated.
    Nanette Veilleux · Simmons College


    You might already know this but I gave Prof Berger my stash of silver nanoparticles ...

  • Chris Gueymard added an answer:
    CPV solar over traditional PV technology - what do you think?
    What are the main technological benefits with CPV solar in terms of cost per MEGAWATT? By making use of multijunction and III-V materials, the efficiency obtained is very high, but surprised why can't this compete with traditional PV?
    Chris Gueymard · Solar Consulting Services

    I agree with Gerro that using CPV for electricity and heat production can be quite interesting. Only a few companies are currently developing this avenue. The overall efficiency goes up to 75% or so, but such systems are only interesting close to industries that need process heat, which is a market niche in a market niche (since high DNI is still required).

  • Nikola Tasić added an answer:
    How do you safely prepare a 40 mM aqueous solution of TiCl4?

    A general procedure in the assembly of dye-sensitized solar cells is to deposit a thin film of TiO2 by submerging the substrate in a 40 mM aqueous TiCl4 solution at 70*C for some period of time. However, the reagent in question, TiCl4, reacts violently upon contact with water and should be handled inertly. I would like to know what the safe procedure and equipment are for preparing the titania precursor solution out of pure TiCl4 and di water. Many thanks!

    Nikola Tasić · University of Belgrade

    While performing this reagent preparation, you should keep both water and bottle containing TiCl4 in the ice bath, due to the high volatility of this compound at room temperature. The best way to add TiCl4 to water is by using syringe, which should also be cooled to approx. 0-5*C. Do not forget to wear gloves, and do everything in the fume hood. Good Luck!

  • Markus Hösel added an answer:
    How do you check the performance of P3HT:PCBM film for device fabrication without making polymer solar cell?

    I am working on printing of P3HT:PCBM film for solar cell application. I want to check whether the active layer will work or not, without making device. I am doing characterization like UV-Vis abs, AFM and thickness. Any other  method which tell about the performance of active layer.

  • Manuel Schnabel added an answer:
    Why is the efficiency of CZTS solar cells synthesized from hydrazine better than other solutions?

    I am working on CZTS thin film solar cell fabrication.I am confused why the CZTS solar cell synthesized from hydrazine could get a PCE more than 11%. However, up to now, based on other solutions, such as oleylamine, the performance is lower than 10%. 

    Manuel Schnabel · Fraunhofer Institute for Solar Energy Systems ISE

    Are all cells from the same lab? Or the 11% is from the literature and the <10% is in your lab? If they are from different labs, there are a million things that could be different, might be the cell structure and nothing to do with the absorber material for example.

  • Jorge Morales Pedraza added an answer:
    Which source of the energy is the safest for the environment ?
    Which source of the energy is the safest for the environment ? which one do you recommend?. what factors we should consider in choosing an energy source?
    Jorge Morales Pedraza · Independent Consultant

    We can say the same thing for others renewable energy sources. They are safe for the environment.

  • Sai-Anand Gopalan added an answer:
    Does anyone have an alternative solution for a processable buffer layer for use in Inverted PSCs?

    Please suggest an alternative solution processable buffer layer (Say metal oxide interlayers like V205, MOx etc or others) for use in inverted polymer solar cells configuration. We don't have evaporation chamber for Silver, gold (or) other metals for use as anode. Please inform any buffer layer which is compatible with Aluminium (Al) electrode for efficient hole extraction in the anode side. Request your kind advice/comments.

    Sai-Anand Gopalan · Kyungpook National University

    Riski Titian, thanks for the useful references. Since, we are not having vacuum chamber for high work function metals based thermal deposition (Au or Ag), we are forced to use only Al electrode. 

  • Sha Anwer Kakil added an answer:
    What is the significance of synthesizing nanoparticles in thin film solar cells?

    Currently, thin films from nanoparticles are widely used in solar cells. What are the other properties that can be improved to improve solar cell efficiency?

    Sha Anwer Kakil · Salahaddin University - Hawler

    it is important for solar cell to reduce the surface reflection of light in order to improve the efficiency of the device.

  • Jethro Betcke added an answer:
    In a-Si:H, are dandling bond defects present in thermal equilibrium conditions in the material identical to DB defects formed by optical degradation?

    See above

    Jethro Betcke · Carl von Ossietzky Universität Oldenburg

    The thermal equilibrium between dangling bonds and weak bonds is described by the defect pool model. Two groups pioneered this model: Bauer/ Schumm  and  Dean/ Powell. However, this work is from the early nineties, you can search for papers who reference their work to find more up to date publications.

  • Brijesh Tripathi added an answer:
    Is there any cost effective and simple technique to make good quality of oxide films by chemical methods?

    I'm working on alkaline earth stannates materials for photovoltaic applications...

    Brijesh Tripathi · Pandit Deen Dayal Petroleum University

    There are many chemical methods, namely Sol-gel, solvothermal, hydrothermal, micelle, inverse micelle, cvd, electrodeposition, electrophoretic deposition, sonochemical, microwave assisted cvd etc. Please refer to: Chem. Rev. 2007, 107, 2891-2959. The paper is attached for your reference.

  • William Taube added an answer:
    How can I measure the current density from IPCE curve for a solar cell?

    Several publications with this kind of information, but I am finding difficulty to measure: from the principle it is there but I have to find intensity of each monochromatic wave. Please can you suggest me.

    William Taube · Central Electronics Engineering Research Institute

    Dear Naresh,

    I agree with the valuable suggestions from Riski, Mauro and Dr. Mehta. I have an offline easy solution for you, if you have some basic understanding of Matlab. Please find attached a simple code written in Matlab which you can use to feed in your "Wavelength" nm Vs "IPCE" (%). Just copy and paste it.

    Step 1: Make "Wavelength" Array and "IPCE" Array

    Step 2: Save it with command "save IPCE_Data.mat"

    Step 3: Run the code "IPCEtoCurrentDensity.m".

    You will get the short circuit current density in mA/cm2. The code is self explanatory.  Feel free to contact me if you have any technical queries related to the code. The code uses the standard AM1.5G database as suggested by Mauro. Let me know if you face any difficulty.


  • Dr. Iva Ninova Kuznetsova added an answer:
    Can perovskite solar cell overcome DSSCs, before their commercialization?
    Future of DSSC.
  • Mukannan Arivanandhan added an answer:
    Which is a very suitable method to synthesize nanoparticles of single phase with controlled size and shape for thin film solar cell applications?

    With the idea of developing a defect free film .

    Mukannan Arivanandhan · Shizuoka University

    I just forgot to mention that the thin film of the wet chemical synthesised nano particle can be made by spin coating and the size and shapes of nano particles can be further modified by rapid thermal annealing (RTA) process at different time intervals. The RTA process is quite good to tune the size of the nano particle coated on the substrates. 

  • Amr Hessein added an answer:
    Can anyone help with polysulfide electrolytes?

    To whom work in quantum dot sensitized solar cell. I prepare polysulfide electrolyte with concentration 1M Na2S and 1M S in distilled water. My problem is after some time I found a green precipitate in the electrolyte. 

    Noting that I dissolve the components by ultrasonic, so is refluxing process could eliminate this action?

    Amr Hessein · Benha University

    in the attached paper, the author talking about refluxing the electrolyte for 45 min. Does the refluxing has an effect on the stability of the electrolyte?  

  • S. Abd.El.Aleem added an answer:
    Why is pentacene a very promising solar cell material?
    What are the major attributes which makes it distinctive from other material of the same group i.e. organic polymer?
    S. Abd.El.Aleem · Fayoum University

    Thank you so much for this interesting comment.

  • Navaratnasamy Karthikeyan added an answer:
    Why use dye sensitized solar cells?

    Why not use of normal dyes (in form of fruits and other similar stuff) instead of the chemical dyes available? Efficiency effects any? 

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