摘要
In this study, a series of random conjugated polymers (PBDB-TBTn) as donors were designed and synthesized. In these polymers, benzodithiophene unit with thiophene conjugated side chains (BDT) are donor part, and two different content of benzo[1,2-c:4,5-c']dithiophene-4,8-dione (BDD) and difluorobenzothiadizole (BT) linked alkylthiophene are acceptor unit. Polymer solar cells (PSCs) were fabricated with ITIC as an acceptor, and over the power conversion efficiency (PCE) of 9%was obtained, with open circuit voltage (Voc) of 0.86 V, short-circuit current density (Jsc) of 16.84 mA/cm^2, and fill factor (FF) of 62.5%. These random conjugated polymers based solar cells are insensitive to solvent additives and thermal annealing. The performance of the device decreases gradually with the increasing of the proportion of fluorinated acceptor unit. The declining efficiency is due to the excessive fluorinated acceptor unit, which leads to over aggregated topography, destroys the effective charge transport pathways, and affects phase separation domain size between the donor and the acceptor. The phenomena are explained by the charge carrier recombination, atomic force microscope (AFM), and transmission electron microscope (TEM). These results indicate that proper addition of fluorinated acceptor units to build random copolymers can enhance the efficiency of organic photovoltaics toward additive-free and thermal annealing-free PSCs.
In this study,a series of random conjugated polymers（PBDB-TBTn）as donors were designed and synthesized.In these polymers,benzodithiophene unit with thiophene conj ugated side chains（BDT）are donor part,and two different content of benzo[1,2-c:4,5-c’]dithiophene-4,8-dione（BDD）and difluorobenzothiadizole（BT）linked alkylthiophene are acceptor unit.Polymer solar cells（PSCs）were fabricated with ITIC as an acceptor,and over the power conversion efficiency（PCE）of 9%was obtained,with open circuit voltage(Voc)of 0.86 V,short-circuit current density(Jsc)of 16.84 mA/cm2,and fill factor（FF）of 62.5%.These random co njugated polymers based solar cells are insensitive to solve nt additives and thermal annealing.The performance of the device decreases gradually with the increasing of the proportion of fluorinated acceptor unit.The declining efficiency is due to the excessive fluorinated acceptor unit,which leads to over aggregated topography,destroys the effective charge transport pathways,and affects phase separation domain size between the donor and the acceptor.The phenomena are explained by the charge carrier recombination,atomic force microscope（AFM）,and transmission electron microscope（TEM）.These results indicate that proper addition of fluorinated acceptor units to build random copolymers can enhance the efficiency of organic photovoltaics toward additive-free and thermal annealing-free PSCs.
基金
the National Natural Science Foundation of China (Nos. 21602150, 51763017, 51863012, 21861025, 51833004)
Natural Science Foundation of Jiangxi Province in China (Nos. 20171ACB21012 and 2018ACB21022)
the Innovation Fund Designated for Graduate Students of Nanchang University(No. CX2018028)
作者简介
Corresponding authors at:Youdi Zhang,College of Chemistry, Nanchang University. Nanchang 330031, China. E-mail addresses:ydzhang2007@ncu.edu.cn;Corresponding authors at:Zhongyi Yuan,E-mail addresses:yuan@ncu.edu.cn;Corresponding authors at:Yiwang Chen,E-mail addresses:ywchen@ncu.edu.cn.
