Solar Cells

Solar Cells

  • Hafiz Muhammad Yar added an answer:
    Can anyone offer advice on synthesising ZnO quantum dots for solar cells?

    1,Octadecylamine.........2..octadecene ...........I want to make ZnO Quantum Dots for Solar Cells, so i read the Article A study of photoluminescence properties and performance improvement of Cd-doped ZnO quantum dots prepared by the sol–gel method........in this article why they use 1,Octadecylamine.........2..octadecene for what purpose except of these compound what other i acn use? and washed rapidly means ? what method to wash Please if some one guide and help me in this regard.

    Hafiz Muhammad Yar · University of Ulsan

    Dear  Kwangyeol Lee

    Thank so much for your information i am following your procedure and let see what will happened at the end of the experiment,

  • Hammad Cheema added an answer:
    How does the use of additives (e.g.ionic-liquid based electrolytes) enhance the stability of a dye-sensitized solar cell?

    Generally it was found that the use of additives in redox mediator [iodide/triiodide] cause not only improved performance but also increase device stability. In particular, I want to know the impact on the device stability. Can it affect the dye-desorption from TiO2 that has direct impact on the long-term stability of DSSCs?

    Hammad Cheema · North Carolina State University

    Yes, some additives do lead to catalytic replacement of NCS, in Ru metal complexes,, in particular. Pls check the reference #45 and 46 in the following publication for possible explanation for your question.   

  • Bill Williams added an answer:
    What is the most appropriate lamp type for handmade solar simulator?

    I need to get a light source that simulate the sunlight in order to test my samples. Can I use "400 W metal halide lamp" or " Halogen lamp" is better?

    Bill Williams · Birkbeck, University of London

    A raw metal halide (HMI) lamp will produce a spectrum that achieves ASTM/IEC Class B spectral match. A raw xenon will require some IR clipping filters to achieve a similar spectral match (see link attached). Metal halide lamps are also cheaper and have a better temporal stability than xenon without the need for feedback control.

  • Dalia Arafa added an answer:
    Can I use the three diode model to simulate the physical behavior of any pv module?

    Can i use the three diode model to simulate the physical behavior of any pv module? Edit
    can i use the three diode model to simulate the physical behavior of any pv module , or there are any restrictions on using this model . if there are any restrictions what are they? why?

    three diode model is valid to simulate the physical behavior of any pv module, or restricted on certain types of pv cell 

    Dalia Arafa · Fayoum University

     great answer

    i read the first paper you attach it , thanks alot prof for your benefit  response , i conclude this  note of using the three diode model when i read paper of 2007 for modeling multicrystalline solar cells, so i think why we don't apply three diode for different multicrystalline solar modules. 

    thanks 

  • Hammad Cheema added an answer:
    How to get good film forming properties for methylammonium lead bromide?

    I tried the solution processing method with 1:3 molar ratio of PbBr2:MABr respectively dissolved in DMF. But when I spin coated the solution on glass substrate, the film was not formed properly and unevenly. I tried several spin coating's speeds and for several times but it didn't improve significantly. Also, I got some orange films and yellow films. 

    Hammad Cheema · North Carolina State University

    In that case, one thing that might help is to treat your substrate with oxygen plasma for 10-15 mintues and then spin coat with the solution.

  • Dalia Arafa added an answer:
    Ask about if the three diode model is valid to present any pv device?

    i want to know if three diode model can present any pv module or restricted only for certain types of pv cell (cell only ).  and why? 

    Dalia Arafa · Fayoum University

    please dear  Trung-Kien Vu ·

    clarify what you want to say, if three diode mmodel is valid for pv module like pv cell or not and why ?

    thanks  

  • Svetlana Polivtseva added an answer:
    How can I synthesize CuInS2 by Chemical Solution Deposition Method ?

    Respected all,

    I synthesize P-type absorber layer of CuInS2 by spin coating method with following salts

    Copper Chloride, Indium Chloride, Thiourea Cu:In:S2  1.1 :1 : 4 with 2-methoxy ethanol or 2-propanol(IPA) as precursor solution. I synthesize CuInS2 on glass substrate with 10 layers at drying temp 300 C. and annealing temp 420 C in Nitrogen atmosphere.

    But, when i did xrd analsis there are several impurity peaks like CuS, In2O3 

    Please prove me some guideline or literature so I can synthesize CuInS2 without any sub-phases  by solution deposition or any other method.

    Regards 

    Jigar Chaudhari

    Svetlana Polivtseva · Tallinn University of Technology

    Dear Jigar, write your system what was used. Real molarity of the salts and deposition atmosphere (air or N2).  There are two main reasons 1. Uncomplexed thiourea decomposes itself . 2. Metal cations form several compleses  -where thiourea ligand and ligands of solvents are in competition. Probably, In (3+) is uncomplexed in conditions of your experiment. So, you have to increase the precursors molar ratio (Me-S) in your parent solution, decrease the drying temperature or change a solvent system used.

  • 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

    I guess this would create locally different quasi-Fermi levels looking like peaks. The charge carriers would then be driven into the 'inactive' regions of the thin film by drift and diffusion. But what do you mean by 'photonic effects'?

  • Hairen Tan added an answer:
    Did the photon recycling effect exist in perovskite solar cells?

    Recently, I did some research work on predicting the efficiency limit of perovskite solar cells [Appl. Phys. Lett. 106, 221104 (2015) http://dx.doi.org/10.1063/1.4922150]. I also added some points in wikipedia [https://en.wikipedia.org/wiki/Perovskite_solar_cell#Physics].

    According to the detailed balance model by Shockley and Queisser, the maximal output power of a solar cell can be achieved if the following set of hypotheses are fulfilled:

    (1)     Carrier populations obey Maxwell-Boltzman statistics. Particularly, the quasi-Fermi levels of electrons and holes are uniformly split through the cell and the split equals the applied voltage. The assumption is reasonable if mobility of photocarriers (electrons and holes) are sufficiently large. Regarding perovskite materials, charge carrier mobility as high as 10 cm2 V-1 s-1 has been observed.

    (2)     Radiative band-to-band (bimolecular) recombination mechanism is the only one existing. Nonradiative recombination, such as Auger recombination, trap (defect) assisted recombination, etc, are ignorable. Different from silicon with an indirect bandgap, perovskite material has a direct band gap. Therefore, Auger recombination is sufficiently suppressed, which has been verified in recent experimental results. Moreover, light emission from perovskite solar cells is dominated by a sharp band-to-band transition that has a radiative efficiency much higher than that of organic solar cells.

    (3)     Internal conversion efficiency reaches 100%. When one photon is absorbed, it produces one electron-hole pair; and when one electron-hole pair recombines, it produces one photon. For perovskite solar cells, the internal quantum efficiency approaches 100%.

    (4)     Photon recycling effect cccurs in the cell. Although a photon will be created by one electron-hole pair recombination during the radiative recombination process, the photon can be reabsorbed at a different spatial location in the cell, which creates a new electron-hole pair. Designs of light trapping and angular restriction can improve the photon reabsorption process and thus maximize solar cell efficiency. For perovskite solar cells, the existing of photon recycling effect is still unclear.

    From my personal point of view, points 1—3 now are clear. The unclear point is point 4. We knew that photon recycling effect has been confirmed in GaAs solar cells recently. Did the effect exist in perovskite solar cells? How to confirm it? I’d like to listen to your opinions.

    Hairen Tan · Delft University of Technology

    Never forget that the light trapping structures may considerably generate higher defects density. In direct bandgap solar cells, all the state-of-the-art devices (including GaAs) are based on flat structure (no light trapping, only AR). As for polycrystalline solar cells, such as Perovskites, the SRH recombination dominates, thus photon-recycling is useless from a practical way. For very high-quality GaAs with extremely low defects density, it is true that photon-recycling can help to improve the efficiency, but only a bit.

  • Abdullah Ashraf added an answer:
    How can you do a sulfurization process safely?
    I going to make sulfurization of copper, indium thin layer. Is it ok to do it with a closed furnace by covering the glass substrate and sulfur power by beaker? 550-580 deg Celsius temperature will be used. Or I should do it at a tube furnace?
    Abdullah Ashraf · Qatar University

    yes

  • Ali Gharaee added an answer:
    What is the perovskite CH3NH3PbI3 refractive index value ?

    Since the first report on a long-term durable solid-state perovskite solar cell with a power conversion efficiency (PCE) of 9.7% in 2012, a PCE as high as 19.3% was demonstrated in 2014, and a certified PCE of 17.9% was shown in 2014. Such a high photovoltaic performance is attributed to optically high absorption characteristics and balanced charge transport properties with long diffusion lengths.

    I am studying now how to improve solar cell with provskite, we actually made many samples in MU labs at electrical engineering department, and start to simulate the results using FDTD, I try now to find for refractive index and extinction coefficient for CH3NH3PbI3 with respect to wavelength.

    Ali Gharaee · Khorasan Institute of Higher Education

    http://pubs.acs.org/doi/abs/10.1021/jz502471h

  • Nilotpal Bhattacharjee added an answer:
    Is it OK to recognize a solar cell by an absorber layer only?

    My paper (a review on indium sulfide buffered chalcopyrite and CdTe solar cells from various deposition techniques) was rejected by a reviewer saying solar cells are recognized by absorbers only and that buffer layer doesn't contribute toward improving the efficiency of a solar cell. I don't agree with this statement. Could anyone shed light on this please? Thank you.

    Nilotpal Bhattacharjee · Assam University

     The capacitance between the absorber  and buffer is significant. Any solar cell when acts as an energy source is depicted by the small curve in the forward biasing region in its I-V characteristics, which can be influenced by the buffer layer as mild disturbance by its electron transport can easily disturb the electrons in the  absorber. Moreover  the absorber is in nano scale or two dimensional than the significance of buffer gets more relevant.

  • Suhail Anjum Abdur Raheem Sayyed added an answer:
    How can I improve short circuit current in Dye Sensitized Solar Cells?

    The solar cells we are making are having good voltage arouen 350 to 500mV but current is low in microAmpere. How to improve current. we are using low cost dyes such as rose bengal and eosing y.

    Suhail Anjum Abdur Raheem Sayyed · Ahmednagar College

    dear sir I could not access the supplemental information. If you could send on my mail sasayyed81@gmail.com then I will be very much thankful to you.

  • Wei E. I. Sha added an answer:
    What's the major challenge of perovskite solar cells?
    It is such a hot topic these days. What's the major challenge in this field? Is it really going to be a mainstream technology?
    Wei E. I. Sha · The University of Hong Kong

    you can read my paper in http://dx.doi.org/10.1063/1.4922150. I also edit wikipedia for perovskite solar cell (physics part).

  • yu-chu Tseng asked a question:
    What is the mechanism of Al bead on the PERC cell ?

    according to our experiments, sometime a few beads happened on the cell 2 dges on the direction of cell conveyed in the co-firer, sometime beads happened on the 4 edges, and sometime we found beads happened on the ends of back contact lines no matter the direction of cell conveyed .  The bead size is very small. The Al film thickness  checked by SEM is not much different between cell center and edges.

  • Harsimran Singh Bindra added an answer:
    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.

    Harsimran Singh Bindra · Amity University

    i am not able to calculate values of Voc for Si, Ge and GaAs as per the formula, please help me out with this problem

  • Hammad Cheema added an answer:
    What is causing the low fill factor of MAPbI3-spiro based solar cell, when current is around 16 mA/cm2 and Voc is 0.9V?

    I had made some Perovskite solar cells, current up to 16mA/cm2 and Voc of 0.9V was achieved but FF was around 26 which was killing the efficiency, and in different cells that is consistent? can you suggest the possible cause.

    Hammad Cheema · North Carolina State University

    After doing XRD, it is quite clear that the method i was using was not reacting all of the PbI2, which might be the reason for low FF, looking forward to make cells with modified method.....

  • Mohammed F Al-Mudhaffer added an answer:
    How do I etch In2O3/Au/Ag coating from an optical grade polyester (PET) film?

    For making flexible solar cell, I need to etch some portion of the PET film coated with In2O3/Au/Ag. I prefer wet etching. Which chemical can be used as etchent?

    Mohammed F Al-Mudhaffer · University of Newcastle

    Use HCL with careful

  • Majid Basafa added an answer:
    How can I design and simulate a sliding mode controller for a nonlinear system such as PV systems (MPPT)?

    Hi

    How can I design and simulate a sliding mode controller for a nonlinear system such as PV systems (MPPT)?

    I am looking for useful articles about sliding-mode control systems.(Design and Simulation)

    Best regards.

    Majid Basafa · Khorasan Institute of Higher Education

    with matlab

  • Manimekalai Ponnusamy added an answer:
    Can MPPT techniques applied to ZVS, ZCS and soft switching converters?
    Can MPPT techniques applied to ZVS,ZCS and soft switching converters?
    Manimekalai Ponnusamy · Selvam College of Technology

    THANK YOU FOR RESPONSE SIR. YOU HAD GIVEN VALUABLE INFORMATION HADEED SIR. 

  • Ananth Saradhi added an answer:
    What are the "Sun Simulator" alternatives?

    I need someone to tell me what are the cost effective  alternatives for sun simulators as a light source. My work is in the photovoltaics area and I need to characterize my solar cell samples.

    Ananth Saradhi · Birla Institute of Technology and Science Pilani

    10 K Euro is expensive for us. Hope to get some cells from infinityPV, Dr.Hosel  :).

    Thanks for the alternative - I can try the real sun method. I just did not know how to convert those readings to STC.

  • Ghada Khedr added an answer:
    How can i cover back contact of my CIGS solar cell through deposition & selenization?

    I'm fabricating CIGS thin films by RF sputtering followed by a high temperature selenization process. I tried using polymer to cover then remove the covered area by organic solvent but it didn't succeed.

    Ghada Khedr · University of Southampton

    Thank you for replying,,, the photoresist unfortunately doesn't go upto 550C

  • Kashif Javaid added an answer:
    Why are silicon solar cell p-layers is thicker than n-layers?

    In silicon solar cell p-layer is thicker than n-layer, why?

    Kashif Javaid · Government College University Faisalabad

    All the above discussion is very useful and scientific. Here i want to add one more point...The purpose to make the width of  N-region is smaller is that, its width  would become less than the diffusion length of holes. It means that holes in  N-region (minority carriers) can easily diffuse to metal electrode before recombining. 

  • Pawan Kumar added an answer:
    Can oxygen octahedra tilting in perovskites be determined by XRD with Lab source or synchrotron ?

    Octahedral tilting

    Pawan Kumar · Indian Institute of Technology Patna

    Thanks sir for your valuable comments. I also have tried with Rietveld refinement of xrd patterns.

  • Neetish Maurya added an answer:
    How can I calculate the amount of dye adsorbed by the photoanodes in DSSC?

    I am trying to measure the amount of dye adsorbed by the photoanode, but I am not able. Can anyone give any suggestions?

    Neetish Maurya · Indian School of Mines

    The same can be done by measuring the conductance of the solution. How ever one  must be careful  that the solute should not contribute towards the observance or conductance. 

    I am also planning the same type of work where I have to measure the amount of surfactant adsorbed on sand particle during EOR operation in oil field. 

  • Kwei Kwang Chang added an answer:
    On the energy balance and energy conversions within a solar cell?

    I would like to confirm the soundness of a simple steady-state energy balance over a solar cell.

    Assume we take a solar cell as the control volume for an energy balance where the electrical conversion efficiency is defined with respect to the incident solar power.

    As shown in the attached energy balance and energy flow diagrams, are the following general equations correct for steady-state operation:

    1. P_inc = P_ref + P_ele + P_conv + P_cond + P_rad
    2. P_inc = P_abs + P_ref
    3. P_abs = P_ele + P_th

    Where:

    1. P_inc is the incident solar power on the solar cell's surface.
    2. P_abs is the solar power absorbed by the solar cell.
    3. P_ref is the solar power reflected from the solar cell's surface.
    4. P_ele is the solar power converted to electrical power.
    5. P_th is the solar power converted to thermal power.
    6. P_conv is power convected to the ambient.
    7. P_cond is power conducted to the substrate.
    8. P_rad is power radiated to the surroundings.
    9. alpha: is the absorptivity of the solar cell.
    10. eta: is the electrical conversion efficiency.

    My uncertainty is rising from the fact that P_ele is defined with respect to P_inc not P_abs and how that would affect the energy balance.

    Also, what is the energy form of P_abs? Clearly, P_abs is an intermediate step in the conversion of solar power into electrical and thermal powers. Does that mean P_abs is in the form of internal chemical power within the semiconductor?

    Any help is highly appreciated.

  • Ravi Ranjan added an answer:
    How can define a new material like InGaBi in Silvaco ATLAS?

    I want to define a new material like InGaBi in my ATLAS program to model a Quantum Dot Solar Cell for my PhD project.

    This new material doesn't exist in default ATLAS materials.

    Ravi Ranjan · Indian School of Mines

    Dear Beghdaoui 

    InAsN is ternary material which is not present in Silvaco. so u see the variation of x for the default material that the new material(InAsN) is based on.

  • Abderrahmane Belghachi added an answer:
    How thick is the buffer layer in solar cells?

    How to determine the optimum buffer layer thickness for a solar cells. Is there any specific range for the buffer layer thickness or special equations from which we can calculate the same.

    Abderrahmane Belghachi · Université de Béchar

    Hi Narendra

    in my opinion there is no magical equation for this problem, the best way of doing it is to use simulation software that are available such as scaps, pc1d , amps,...

    you can run the program for different thicknesses values of the buffer then you can see where is the optimized thickness

    yours sincerely.

    A. Belghachi

  • Alan L. Fahrenbruch added an answer:
    Did any one know the full spectrum of Ultra-high-performance lamp?

    I want to use a Ultra-high-performance lamp as a light source in measuring the J-V curve of solar cell. But I want to know first the full spectrum of this lamp. does it emits in the UV range or only the visible and IR range?

    Alan L. Fahrenbruch · self employed

    Perhaps the simplest and least expensive solution is the ELH lamp, used in slide projectors and the fit for the solar spectrum is reasonable for some purposes.  Attached is a paper about solar simulation with spectra for various lamps.  If you use a slide projector, be aware that they sometimes include an IR filter which would possibly change the spectrum and would have to be removed.

  • Hammad Cheema added an answer:
    Organo metal halide perovskite are the best to date in photovoltaic devices, but why could oxide perovskites not in the same manner?e.g. CaTiO3?

    solar cells 

    Hammad Cheema · North Carolina State University

    The physical mechanism of the photovoltaic effect in ferroelectrics is not
    completely understood. And oxide so far mostly result in less than 1% efficiency. You can check this reference, 

    D. Cao, C. Wang, F. Zheng, W. Dong, L. Fang and M. Shen,
    Nano Lett., 2012, 12, 2803–2809.

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