激子
光激发
激发态
有机太阳能电池
接受者
单重态裂变
单重态
三重态
超快激光光谱学
载流子
化学
电荷(物理)
材料科学
原子物理学
光化学
化学物理
光电子学
物理
凝聚态物理
光谱学
聚合物
有机化学
量子力学
作者
Kazuki Kohzuki,Rei Shirouchi,Shin‐ichiro Natsuda,Toshiharu Saito,Yuji Sakamoto,Yasukatsu Tamai
出处
期刊:Solar RRL
[Wiley]
日期:2023-07-12
卷期号:7 (17)
标识
DOI:10.1002/solr.202300359
摘要
Suppressing charge recombination is pivotal for further improving the power conversion efficiency of organic solar cells (OSCs). The bimolecular recombination of free charge carriers leads to the formation of both singlet and triplet charge transfer (CT) states at a ratio of 1:3 when considering simple spin statistics, meaning that charge recombination via the triplet excited state is the main deactivation channel for OSCs. Although the formation of local triplet excitons through back charge transfer from triplet CT states is thought to be a terminal loss process, it is shown that charge separation from triplet excitons can occur in nonfullerene acceptor (NFA)‐based OSCs. To reveal the triplet exciton dynamics, a triplet sensitizer PtTPBP is doped into an OSC consisting of PM6 and Y6 as an electron donor and acceptor, respectively. Upon photoexcitation of PtTPBP, triplet excitons are formed, which subsequently transfer their energy to Y6, resulting in Y6 triplet excitons formation. Based on transient absorption and external quantum efficiency measurements, clear experimental evidence of charge photogeneration from Y6 triplet excitons at the PM6:Y6 interface is provided. This study highlights the importance of minimizing the energy difference between the singlet and triplet excited states of NFAs to suppress charge recombination.
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