激子
轨道能级差
超快激光光谱学
离解(化学)
化学物理
有机太阳能电池
材料科学
分子
光激发
分子物理学
化学
光化学
聚合物
原子物理学
物理化学
激发态
物理
光学
凝聚态物理
激光器
有机化学
复合材料
作者
Junyi Feng,Guanzhao Wen,Rong Hu,Jun Peng,H. Lü,Ningjiu Zhao,Xianshao Zou,Wei Zhang
出处
期刊:Solar RRL
[Wiley]
日期:2023-06-30
卷期号:7 (16)
被引量:1
标识
DOI:10.1002/solr.202300372
摘要
Recent research has revealed that low‐energy offset polymer solar cells (PSCs) are capable of a power conversion efficiency of over 19%. However, it is unclear how energy offsets and the charge photogeneration process are correlated. Herein, the effect of energy offsets on charge photogeneration dynamics for Y‐series molecules (Y5, Y6, Y10, and BTP‐4F‐12)‐based PSCs with the variations of the lowest unoccupied molecular orbital energy offsets (Δ E LUMO ) of 0.11–0.42 eV and the highest occupied molecular orbital energy offsets (Δ E HOMO ) of 0.08–0.23 eV utilizing steady‐state and time‐resolved spectroscopies is studied. The steady‐state measurement shows that the probability of photoluminescence quenching via energy transfer for the donor exciton reduces with the increasing Δ E LUMO. It is found that even in PM6:Y6 with the highest Δ E LUMO , ≈18% of PM6 exciton dissociated via the path of “energy transfer first and then hole transfer,” manifesting the energy transfer also plays a vital role in the process of exciton dissociation. Furthermore, it is found that the PM6 exciton can efficiently dissociate under the Δ E LUMO of 0.11 eV. After photoexcitation of the Y‐series molecule acceptors, the exciton dissociation efficiency enhances with the increase of Δ E HOMO . Besides, the higher energy offsets, the lower charge recombination rate in the ultrafast timescale has been found from the transient absorption measurement. These findings reveal that energy offsets are important for charge photogeneration and recombination in an ultrafast timescale for Y‐series molecule‐based PSCs, which may shed light on the design of high‐performance PSCs.
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