Impact of morphology change on hole transfer dynamic during charge separation process

Dong Chan Lee; Jiho Ryu; Chang-Mok Oh; In-Wook Hwang; Shinuk Cho

doi:10.1117/12.2684587

6 October 2023 Impact of morphology change on hole transfer dynamic during charge separation process

Dong Chan Lee, Jiho Ryu, Chang-Mok Oh, In-Wook Hwang, Shinuk Cho

Proceedings Volume PC12660, Organic, Hybrid, and Perovskite Photovoltaics XXIV; PC126600Z (2023) https://doi.org/10.1117/12.2684587
Event: SPIE Organic Photonics + Electronics, 2023, San Diego, California, United States

Conference Poster

Abstract

Although it has been clearly elucidated that the change in the overall bulk-heterojunction (BHJ) morphology of PM6:Y6 induced by the difference in solvents results in a variation in the performance of the entire solar cell, the charge dynamics during the charge separation process induced by morphological changes have not yet been deeply studied. Based on mobility and photocurrent-related studies, it has been inferred that holes are deeply involved in these charge generation and separation processes. The decrease in exciton dissociation probability observed in the PM6:Y6 solar cell fabricated using CB (PM6:Y6-CB) was found to be due to the change in the hole transfer state caused by morphological changes. For the PM6:Y6 solar cell fabricated using CF (PM6:Y6-CF), it was determined that the density of the state (DOS) of the effective hole transfer state (hECT) was small, as hECT and Y6 HOMO were almost degenerate, and the lower hECT, which can interfere with hole transfer, was also formed minimally. However, for PM6:Y6-CB, the overlapping region of hECT and the highest occupied molecular orbital (HOMO) of Y6 shifted towards the lower energy side (upper hECT), and a lower effective hECT that can act as a defect was significantly formed. These facts obtained by EL deconvolution were clearly confirmed in time-resolved photoinduced absorption spectroscopy. As a result, it is concluded that the decrease in fill factor (FF) and current density (JSC) in PM6:Y6-CB is due to the degradation of hole transfer from Y6 HOMO to PM6 HOMO. This analysis shows that the morphological changes in non-fullerene acceptor (NFA) solar cells affect the formation of hole transfer levels, which in turn affect the charge separation efficiency.

Citation Download Citation

Dong Chan Lee, Jiho Ryu, Chang-Mok Oh, In-Wook Hwang, and Shinuk Cho "Impact of morphology change on hole transfer dynamic during charge separation process", Proc. SPIE PC12660, Organic, Hybrid, and Perovskite Photovoltaics XXIV, PC126600Z (6 October 2023); https://doi.org/10.1117/12.2684587

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