An improved circuit model for polymer solar cells

Gaur, Ankita; Kumar, Pankaj

doi:10.1002/pip.2345

Cited by 23 publications

(25 citation statements)

References 48 publications

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“…As the physics of PSCs is different, consideration of conventional solar cell model for PSCs is unphysical. Very recently, we have developed a model, which explains correctly the behavior of PSCs . For modeling of PSCs, the active organic layer was considered to be a single semiconductor with HOMO of the donor and LUMO of the acceptor, with hole mobility equal to that of donor and electron mobility equal to that of acceptor molecules.…”

Section: Resultsmentioning

confidence: 99%

“…We found that the dark characteristics could be explained by considering two diodes D1 and D2 connected in parallel together in opposite polarity along with shunt and series resistances (see inset (a) of Fig. ) and the J–V relation could be written as,

\begin{array}{l} left & J = J_{s 1} (V - JA R_{s}) (exp (\frac{q ((), V - italicJA R_{s})}{n_{1} italickT}) - 1) \\ left & - J_{s 2} (exp (\frac{- q ((), V - italicJA R_{s})}{n_{2} italickT}) - 1) + \frac{V - JA R_{s}}{A R_{p}} - J_{italicph} (V) \end{array},

where J s 1 ( V‐JAR s ) and J s 2 are, respectively, the reverse bias current densities in the two diodes, n 1 and n 2 are their ideality factors, R s and R p are, respectively, the parasitic series and shunt resistances. J s 1 ( V‐JAR s ) depends on the charge carrier mobilities, effective density of states, interface barriers for charge carrier injection, V bi and the sample thickness.…”

Section: Resultsmentioning

confidence: 99%

“…Compared to dark, R p decreased for both the samples under illumination and showed almost no variation with time for sample A ; however, in case of sample B , it increased rapidly after ~ 89 h. The different degradation rates in R p for the two samples are because of ambience exposure to the active layer of sample B . Under illumination, the reduction in R p can be understood in terms of photo‐induced doping of the active layer which is represented by addition of photo‐induced shunt resistance across the existing R p in dark . Increment in R s is because of increment in bulk resistivity due to reduction in charge carrier mobilities, formation of traps and increment in contact resistance.…”

Section: Resultsmentioning

confidence: 99%

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Effect of degradation on electronic properties of polymer solar cells

Gaur

Kumar

2013

Polymers for Advanced Techs

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We present here the effect of degradation on electronic properties of polymer solar cells. Investigations were performed on two types of solar cells based on the bulk‐heterojunction network of poly(3‐hexylthiophene) and phenyl [6,6] C61 butyric acid methyl ester, one with slow degradation whereas other with faster degradation. Samples were prepared in identical conditions with controlled atmosphere, but for faster degradation, one of the samples was exposed to ambient air (rich in O2 and H2O molecules) before deposition of top metal electrode. The sample with slow degradation showed linear degradation in short circuit current density (Jsc), whereas the sample with faster degradation exhibited exponential degradation in Jsc. Linear degradation happens due to degradation in the active layer only whereas the exponential degradation is because of through degradation of the solar cell. The effect of degradation is investigated on different diode parameters. Because of different degradation processes in the two samples, the variations in diode parameters with time are different. Copyright © 2013 John Wiley & Sons, Ltd.

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Section: Resultsmentioning

confidence: 99%

\begin{array}{l} left & J = J_{s 1} (V - JA R_{s}) (exp (\frac{q ((), V - italicJA R_{s})}{n_{1} italickT}) - 1) \\ left & - J_{s 2} (exp (\frac{- q ((), V - italicJA R_{s})}{n_{2} italickT}) - 1) + \frac{V - JA R_{s}}{A R_{p}} - J_{italicph} (V) \end{array},

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Effect of degradation on electronic properties of polymer solar cells

Gaur

Kumar

2013

Polymers for Advanced Techs

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“…The same phenomenon was also observed by other groups that the R P will decrease after increasing illumination intensity. 20,24,39 This phenomenon not only indicates that R P should not be a fixedvalue resistance, but also reveals that the current leakage through short-circuit channels is only a small proportion of the total J leak . Considering there is a charge collection process for the separated charges transport to the electrode, Hecht equation was used to modify the leak current item.…”

Section: Model Simulatingmentioning

confidence: 95%

“…Herein, formulating equations in term of semiconductor theory to simulate the current-voltage characteristics becomes a very useful way to reveal these current losses. [18][19][20] So far several models such as one-diode model 19 , two-diode model 21 , three-diode model 22 and any other models [23][24][25] have been built to describe various photovoltaic systems. In our previous work, we reported two small molecules for photovoltaic application named DR3TBDTT-HD and DR3TBDT2T ( Fig.…”

Section: Introductionmentioning

confidence: 99%

Device characterization and optimization of small molecule organic solar cells assisted by modelling simulation of the current–voltage characteristics

Zuo

Wan

Long

et al. 2015

Phys. Chem. Chem. Phys.

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In order to understand the photovoltaic performance differences between the recently reported DR3TBTT-HD and DR3TBDT2T based solar cells, a modified two-diode model with Hecht equation was built to simulate the corresponding current-voltage characteristics. The simulation results reveal that the poor device performance of the DR3TBDTT-HD based device mainly originated from its insufficient charge transport ability, where an average current of 5.79 mA cm(-2) was lost through this pathway at the maximum power point for the DR3TBDTT-HD device, nearly three times as large as that of the DR3TBDT2T based device under the same device fabrication conditions. The morphology studies support these simulation results, in which both Raman and 2D-GIXD data reveal that DR3TBTT-HD based blend films exhibit lower crystallinity. Spin coating at low temperature was used to increase the crystallinity of DR3TBDTT-HD based blend films, and the average current loss through insufficient charge transport at maximum power point was suppressed to 2.08 mA cm(-2). As a result, the average experimental power conversion efficiency of DR3TBDTT-HD based solar cells increased by over 40%.

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Quantifying Efficiency Loss of Perovskite Solar Cells by a Modified Detailed Balance Model

Sha

Zhang

Wang

et al. 2017

Advanced Energy Materials

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mechanism and quantify the efficiency loss for perovskite solar cells.The analysis and quantification of efficiency loss of solar cells can be done by the drift-diffusion model, [24,25] circuit model, [26,27] and detailed balance model. [28,29] Due to a high nonlinearity of coupled equations and a complex device configuration, drift-diffusion model is difficult to retrieve simulation parameters from the measured current density-voltage (J-V) curves. The parameters include recombination rate, mobility, energy levels (e.g., conduction band, valence band, and work function), effective density of states, and injection/extraction barrier heights. Furthermore, the drift-diffusion model is nontrivial to describe the photon recycling effect correctly. [30] Concerning the circuit model, it requires to retrieve five parameters in modeling. Hence, the uniqueness of the parameters is questionable. Also, the ideality factor in the circuit model has ambiguous physical meaning and cannot quantitatively represent radiative recombination (photon recycling) and nonradiative (Auger and Shockley-Read-Hall) recombination separately. Additionally, while the traditional detailed balance model demonstrates a strong capability to predict the efficiency limit of an ideal solar cell, the model cannot quantify the energy loss of a practical solar cell including optical and electrical (thermodynamic) loss. In this work, a revised detailed balance model is proposed to unveil the loss mechanism and quantify the loss factors of perovskite solar cells. Through investigating the device performance of various fabricated perovskite solar cells, the three dominant loss factors of optical loss, nonradiative recombination loss, and ohmic loss are identified quantitatively. The perovskite-interface-induced surface recombination, ohmic loss, and current leakage are also analyzed. Consequently, the work offers a guideline to the researchers for optimizing perovskite solar cells and ultimately approaching the Shockley-Queisser limit of photovoltaics. [29] Results and Discussion TheoryIn order to understand the loss mechanism and qualify loss factors, we propose the revised detailed balance model, which is expressed as A modified detailed balance model is built to understand and quantify efficiency loss of perovskite solar cells. The modified model captures the light-absorption-dependent short-circuit current, contact and transport-layermodified carrier transport, as well as recombination and photon-recyclinginfluenced open-circuit voltage. The theoretical and experimental results show that for experimentally optimized perovskite solar cells with the power conversion efficiency of 19%, optical loss of 25%, nonradiative recombination loss of 35%, and ohmic loss of 35% are the three dominant loss factors for approaching the 31% efficiency limit of perovskite solar cells. It is also found that the optical loss climbs up to 40% for a thin-active-layer design. Moreover, a misconfigured transport layer introduces above 15% of energy loss. Finally, the perovskit...

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An improved circuit model for polymer solar cells

Cited by 23 publications

References 48 publications

Effect of degradation on electronic properties of polymer solar cells

Effect of degradation on electronic properties of polymer solar cells

Device characterization and optimization of small molecule organic solar cells assisted by modelling simulation of the current–voltage characteristics

Quantifying Efficiency Loss of Perovskite Solar Cells by a Modified Detailed Balance Model

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