Understanding the Effect of Sequential Deposition Processing for High-Efficient Organic Photovoltaics to Harvest Sunlight and Artificial Light

Abstract

As the market of the Internet of Things (IoT) increases, great attention has been paid to the development of high-efficient organic photovoltaics (OPVs) utilizing artificial light. However, in a real indoor condition, the power density contribution of the artificial light cannot exceed 35% in the combination of indoor and outdoor irradiation, which indicates that the illumination of sunlight cannot be ignored during daytime. Hence, it is urgent to develop high-efficient OPVs in indoor conditions taking into account both sunlight and artificial light. In this work, a novel asymmetric molecule TB-4F was synthesized to trade-off the absorption spectrum that can be applied under both artificial light and sunlight. In conventional bulk-heterojunction (C-BHJ), it was figured out that due to nonoptimal morphology some carriers failed to be efficiently collected. Herein, a sequential deposition bulk-heterojunction (SD-BHJ) as an alternative fabrication method successfully enhanced the performance of OPVs, under both artificial light and sunlight, which was attributed to the favorable microstructure being vertically distributed in the active layer. Notably, the PCE was significantly increased by 25% for SD-BHJ compared to C-BHJ under artificial light, owing to the strong effect of trap-assisted recombination and dark current on PCE in the condition of low carrier density. Our result indicates that an asymmetric molecule with a blue-shifted spectrum fabricated by SD-BHJ can be a promising candidate that can be applied in indoor environments to harvest sunlight and artificial light simultaneously.

Ti3C2Tx/PEDOT:PSS Composite Interface Enables over 17% Efficiency Non-fullerene Organic Solar Cells

“…In order to explain the charge recombination of the device with different doping contents of Ti 3 C 2 T x , the variation of V oc depending on the incident light intensity ( P light ) was measured. The results were linearly fitted by logarithmic processing of the scatter plot of the test results according to the equation ­(shown in Figure a), where K B is Avogadro’s constant, T is the temperature, and S is the slope of the straight line after the fitting. Usually when the value of n is closer to 1, the charge recombination may be dominated by the bimolecular recombination in the whole system, and typically, bimolecular recombination correlates with free charge recombination at the D / A interface.…”

Recent advances in small molecular design for high performance non-fullerene organic solar cells

“…71 Solar cells with Y6-based asymmetric acceptors and polymer donors as the active layer achieved PCE higher than 15%. 100,101 In order to investigate the impact of molecular interaction and orientation on energy loss in organic solar cells, two benzo[1,2-b:4,5-b′]difuran polymers P-FT and P-FP (Fig. 7b) together with two electron acceptors Y6 and m-ITIC were employed by Zhang and co-workers to fabricated solar cells.…”

“…71 Solar cells with Y6-based asymmetric acceptors and polymer donors as the active layer achieved PCE higher than 15%. 100,101…”

Asymmetric Substitution of End‐Groups Triggers 16.34% Efficiency for All‐Small‐Molecule Organic Solar Cells

“…Serving as a next-generation photovoltaic application, the organic solar cell (OSC) has witnessed great progress in power conversion efficiency (PCE) from less than 5% to over 18%. [1][2][3][4][5][6] Benefiting from their unique properties like lowcost, lightweight, mechanical flexibility, and semitransparency, [7][8][9][10] OSCs show the promising commercial application in wearable electronics, building-integrated photovoltaic, [11,12] etc. The bulk heterojunction (BHJ), which consists of a donor and an acceptor, is now a wellknown prerequisite to achieve efficient charge extraction and transport.…”