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

作　　者：Bo Xiao Yingjie Zhao Ailing Tang Haiqiao Wang Jing Yang Erjun Zhou 

机构地区：[1]CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China [2]University of Chinese Academy of Sciences, Beijing 100049, China [3]State Key Laboratory of Organic-Inorganic Composite, Beijing University of Chemical Technology, Beijing 100029, China

出　　处：《Science Bulletin》2017年第18期1275-1282,共8页科学通报（英文版）

基　　金：supported by the National Key Research and Development Program of China (2017YFA0206600);the Key Research Program of Frontier Sciences, Chinese Academy of Sciences (QYZDB-SSW-SLH033);the National Natural Science Foundation of China (51673048, 51473040 and 21602040);the Natural Science Foundation of Beijing (2162045)

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.The open-circuit voltage(V_(oc))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 V_(oc)and power conversion efficiency(PCE).Here,a new benzotriazole(BTA)-based NFSMA,BTA7 was synthesized by adopting A_2@A_1ADAA_1@A_2type molecular backbone.By using a strong electron-accepting unit of malononitrile(M)as terminal segment A_2,BTA7 demonstrates strong crystallinity,red-shifted absorption spectrum and down-shifted lowest unoccupied molecular orbital(LUMO)energy levels in comparison with BTA_1and BTA_2.Organic solar cells(OSCs)based on PTB7-Th:BTA7 realized a high V_(oc)of 1.05 V with a moderate PCE of 4.60%.The energy loss(E_(loss)=E_gàe V_(oc))of 0.53 e V is lower than the experiential minimum value of0.6 e V,which indicates PTB7-Th still has large potential to improve the V_(oc)and photovoltaic performance after the development of novel electron acceptors.

关 键 词：Benzotriazole （BTA） Malononitrile Fullerene-free solar cells Non-fullerene acceptor PTB7-Th 

分 类 号：TM914.4[电气工程—电力电子与电力传动]