Subtle Effect of Alkyl Substitutedπ-Bridges on Dibenzo[a,c]phenazine Based Polymer Donors towards Enhanced Photovoltaic Performance  

作　　者：Chun-Xian Ke Xue Lai Heng-Tao Wang Ming-Rui Pu Tahir Rehman Yu-Lin Zhu Feng He 

机构地区：[1]Shenzhen Grubbs Institute and Department of Chemistry,Southern University of Science and Technology,Shenzhen,518055,China [2]Guangdong Provincial Key Laboratory of Catalysis,Southern University of Science and Technology,Shenzhen,518055,China

出　　处：《Chinese Journal of Polymer Science》2022年第8期889-897,I0007,共10页高分子科学（英文版）

基　　金：This work was financially supported by the National Natural Science Foundation of China(Nos.21733005 and 21975115);the Shenzhen Fundamental Research Program(Nos.JCYJ20190809163011543,JCYJ20200109140801751 and JCYJ20210324120010028);the Guangdong Provincial Key Laboratory of Catalysis(No.2020B121201002);the Guangdong Innovative and Entrepreneurial Research Team Program(No.2016ZT06G587);the Shenzhen Sci-Tech Fund(No.KYTDPT 20181011104007).We also thank the SUSTech Core Research Facilities for AFM and TEM measurements.

摘　　要：Selection of the strategically substituted alkyl chains has a significant effect to modulate the physical properties of conjugated polymers,electro-optical characteristics,and active layer morphology of the corresponding polymer solar cells(PSCs).Herein,we systematically synthesized three dibenzo[a,c]phenazine based D-π-A donor polymers named PBP-C0,PBP-C8,and PBP-C6 with different alkyl substitutions on thiopheneπ-bridges,without alkyl,2-ethylhexyl and n-hexyl groups,respectively.The absence of the alkyl chain(PBP-C0)on theπ-bridge caused poor solubility and unfavorable miscibility with the Y5 acceptor,leading to the lower photovoltaic performance.The bulky alkyl chain of 2-ethylhexyl on theπ-bridge group caused the twisting of PBP-C8 conjugated backbone,which limits the charge transport and also compromises the photovoltaic performance.In contrast,the PBP-C6-with flexible linear alkyl chains has almost planar curvature geometry resulting in the small uniform domain size and appropriate phase separation in the blend film morphology.These favorable properties enhanced the exciton generation to dissociation,charge carrier mobility,and also lowered the charge recombination.Among three polymers,PBP-C6-based devices exhibit the best PCE of 11.60%.From these results,thiopheneπ-bridge alkyl substitution demonstrated an important strategy to adjust energy level,absorption,and phase separation morphology to enhance the photovoltaic performance of the PSCs.

关 键 词：π-Bridge Alkyl chain engineering PHENAZINE Polymer donor Polymer solar cell 

分 类 号：TQ317[化学工程—高聚物工业] TM914.4[电气工程—电力电子与电力传动]