Origin of Open-Circuit Voltage Loss in Polymer Solar Cells and Perovskite Solar Cells

Kim, Hyung Do; Yanagawa, N.; Shimazaki, Ai; Endo, Masaru; Wakamiya, Atsushi; Ohkita, Hideo; Benten, Hiroaki; Ito, Shinzaburo

doi:10.1021/acsami.7b03694

Cited by 36 publications

(43 citation statements)

References 77 publications

(190 reference statements)

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“…In fullerene systems, there are a few examples breaking this Eloss limit, but advances in non-fullerene SMAs has led to more and more systems that combat this problem. Various attempts to reduce this offset by lowering the LUMO level of the acceptor material have resulted in a voltage loss and a drop in VOC, PCE and external quantum efficiency (EQE) [1,32,33]. Other groups have demonstrated an improved VOC in polymer-fullerene systems, with values exceeding 1 V, but always at the cost of JSC [34,35] or optical losses [6].…”

Section: Discussion Of Charge Separation Recombination and Voc Lossmentioning

confidence: 99%

A review of non-fullerene polymer solar cells: from device physics to morphology control

2019

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The rise in power conversion efficiency of organic photovoltaic (OPV) devices over the last few years has been driven by the emergence of new organic semiconductors and the growing understanding of morphological control at both the molecular and aggregation scales. Non-fullerene OPVs adopting p-type conjugated polymers as the donor and n-type small molecules as the acceptor have exhibited steady progress, outperforming PCBM-based solar cells and reaching efficiencies of over 14 % in 2018. This review starts with a refreshed discussion of charge separation, recombination, and VOC loss in non-fullerene OPVs, followed by a review of work undertaken to develop favorable molecular configurations required for high device performance. We summarize several key approaches that have been employed to tune the nanoscale morphology in non-fullerene photovoltaic blends, comparing them (where appropriate) to their PCBM-based counterparts. In particular, we discuss issues ranging from materials chemistry to solution processing and post-treatments, showing how this can lead to enhanced photovoltaic properties. Particular attention is given to the control of molecular configuration through solution processing, which can have a pronounced impact on the structure of the solid-state photoactive layer. Key challenges, including green solvent processing, stability and lifetime, burn-in, and thickness-dependence in non-fullerene OPVs are briefly discussed.

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Section: Discussion Of Charge Separation Recombination and Voc Lossmentioning

confidence: 99%

A review of non-fullerene polymer solar cells: from device physics to morphology control

2019

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“…In this equation, V G0 is the V oc achievable at 0 K, and γ is a temperature‐dependent parameter of the material (usually ≈3). According to the above equation with an assumed V G0 of 1.56 V, the expected V oc reduction is 120 mV when Δ T is 60 °C (d V oc /d T is ≈−2.0 mV K −1 ), while the measured V oc reduction is only 50 mV. The measured J sc also decreased, while the J sc of ideal solar cells should increase slightly.…”

Section: Photovoltaic Parameters Of the Various Device Configurationsmentioning

confidence: 90%

Perovskite Solar Cells with Inorganic Electron‐ and Hole‐Transport Layers Exhibiting Long‐Term (≈500 h) Stability at 85 °C under Continuous 1 Sun Illumination in Ambient Air

et al. 2018

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Despite the high power conversion efficiency (PCE) of perovskite solar cells (PSCs), poor long-term stability is one of the main obstacles preventing their commercialization. Several approaches to enhance the stability of PSCs have been proposed. However, an accelerating stability test of PSCs at high temperature under the operating conditions in ambient air remains still to be demonstrated. Herein, interface-engineered stable PSCs with inorganic charge-transport layers are shown. The highly conductive Al-doped ZnO films act as efficient electron-transporting layers as well as dense passivation layers. This layer prevents underneath perovskite from moisture contact, evaporation of components, and reaction with a metal electrode. Finally, inverted-type PSCs with inorganic charge-transport layers exhibit a PCE of 18.45% and retain 86.7% of the initial efficiency for 500 h under continuous 1 Sun illumination at 85 °C in ambient air with electrical biases (at maximum power point tracking).

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“…The V OC of a PSC is always less than the optical bandgap of the active layer. The detailed origin of the V OC in PSCs falls outside the scope of this manuscript, however, for the purposes of this manuscript, let us consider that the V OC is related to the bandgap of the material by some combination of losses in potential energy (V loss ) as photoexcited charge carriers are generated and extracted from the device (Equation ).

V_{O C} = {normalE}_{normalg} / q - {normalV}_{loss} .

PCE = \min [\int_{300 n m}^{italicλ o n s e t} F l u x false(italicλ false) * {QE}_{fr} false(italicλ false) normald italicλ, \int_{300 n m}^{λ o n s e t} F l u x false(italicλ false) * {QE}_{bk} false(italicλ false) false(1 - {QE}_{fr} false(italicλ false) false) normald italicλ false)] * ({normalE}_{g (fr)} / q - {normalV}_{loss (fr)} + {normalE}_{g (bk)} / q - {normalV}_{loss (bk)}) * FF .

…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modeling and implementation of tandem polymer solar cells using wide‐bandgap front cells

Choi

Hoang

et al. 2019

Carbon Energy

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Tandem device architectures offer a route to greatly increase the maximum possible power conversion efficiencies (PCEs) of polymer solar cells, however, the complexity of tandem cell device fabrication (such as selecting bandgaps of the front and back cells, current matching, thickness, and recombination layer optimization) often result in lower PCEs than are observed in single‐junction devices. In this study, we analyze the influence of front cell and back cell bandgaps and use transfer matrix modeling to rationally design and optimize effective tandem solar cell structures before actual device fabrication. Our approach allows us to estimate tandem device parameters based on known absorption coefficients and open‐circuit voltages of different active layer materials and design devices without wasting valuable time and materials. Using this approach, we have investigated a series of wide bandgap, high voltage photovoltaic polymers as front cells in tandem devices with PTB7‐Th as a back cell. In this way, we have been able to demonstrate tandem devices with PCE of up to 12.8% with minimal consumption of valuable photoactive materials in tandem device optimization. This value represents one of the highest PCE values to date for fullerene‐based tandem solar cells.

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Origin of Open-Circuit Voltage Loss in Polymer Solar Cells and Perovskite Solar Cells

Cited by 36 publications

References 77 publications

A review of non-fullerene polymer solar cells: from device physics to morphology control

A review of non-fullerene polymer solar cells: from device physics to morphology control

Perovskite Solar Cells with Inorganic Electron‐ and Hole‐Transport Layers Exhibiting Long‐Term (≈500 h) Stability at 85 °C under Continuous 1 Sun Illumination in Ambient Air

Modeling and implementation of tandem polymer solar cells using wide‐bandgap front cells

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