PTB7-Th based organic solar cell with a high Voc of 1.05 V by modulating the LUMO energy level of benzotriazole-containing non-fullerene acceptor

• 来源期刊: 科学通报（英文版）
• 年，卷（期）: 2017,（18）
• 页码范围: 1275-1282
• 页数: 8页
• 语种: 英文

摘要

The open-circuit voltage (Voc) of classical photovoltaic polymers,such as P3HT and PTB7-Th,are always restricted when combining with fullerene derivatives,due to the difficulty of modulating the energy levels of fullerene derivatives.Thus,design of new non-fullerene small molecule acceptor (NFSMA) is very significant to match with these mature polymer donors and improve the Voc and power conversion efficiency (PCE).Here,a new benzotriazole (BTA)-based NFSMA,BTA7 was synthesized by adopting A2=A1-D-A1=A2 type molecular backbone.By using a strong electron-accepting unit of malononitrile (M) as terminal segment A2,BTA7 demonstrates strong crystallinity,red-shifted absorption spectrum and down-shifted lowest unoccupied molecular orbital (LUMO) energy levels in comparison with BTA1 and BTA2.Organic solar cells (OSCs) based on PTB7-Th:BTA7 realized a high Voc of 1.05 V with a moderate PCE of 4.60％.The energy loss (Eloss =Eg-eVoc) of 0.53 eV is lower than the experiential minimum value of 0.6 eV,which indicates PTB7-Th still has large potential to improve the Voc and photovoltaic performance after the development of novel electron acceptors.