A new perspective for organic solar cells: triplet nonfullerene acceptors

• 来源期刊: 中国科学:化学（英文版）
• 年，卷（期）: 2018,（6）
• 页码范围: 637-638
• 页数: 2页
• 语种: 英文

摘要

In the last decade, the rapid development of bulk heterojunction (BHJ) organic solar cells (OSCs) has been witnessed and the power conversion efficiencies (PCEs) have reached over 13％[1].Though fullerene derivatives have played dominant roles for BHJ OSCs, nonfullerene acceptors recently showed a promising potential in replacing fullerene derivatives since they possess readily tunable bandgaps, strong and broad absorption, and low cost production[2, 3].The working mechanism of OSCs includes four photophysical processes: (1) photon absorption and exciton generation, (2) exciton diffusion, (3) exciton dissociation, and (4) charge carrier transport and collection.Thus, the efficiency of OSCs is the combination of the efficiency of each step.Apparently, one effective strategy to improve the efficiency is increasing the exciton diffusion distance to enhance excitons dissociating into free carriers at donor/acceptor interfaces.Thus, triplet state materials can provide sufficient time for charge transfer (CT) state to dissociate into free charges.However, the roles of triplet excitons in OSCs remain unclear, so it is essential to investigate triplet materials to study the mechanism.