共轭体系
带隙
聚合物
轨道能级差
噻吩
材料科学
聚合物太阳能电池
光伏系统
化学
开路电压
高分子化学
光电子学
有机化学
分子
电压
物理
电气工程
工程类
量子力学
复合材料
作者
Jianhui Hou,Mi‐Hyae Park,Shaoqing Zhang,Yan Yao,Limin Chen,Juo‐Hao Li,Yang Yang
出处
期刊:Macromolecules
[American Chemical Society]
日期:2008-07-23
卷期号:41 (16): 6012-6018
被引量:746
摘要
ABSTRACT: Bandgap and molecular energy level control are of great importance in improving photovoltaic properties of conjugated polymers. A common approach to tuning these parameters is to modify the structure of conjugated polymers by copolymerizing with different units. In this paper, research work focuses on the synthesis of benzo[1,2-b:4,5-b′]dithiophene (BDT) with different conjugated units and their photovoltaic performance. Eight new BDT-based polymers with commonly used conjugated units, including thiophene, benzo[c][1,2,5]thiadiazole (BT), thieno[3,4-b]pyrazine (TPZ), etc., were synthesized. The bandgaps of the polymers were tuned in the range of 1.0-2.0 eV, and their HOMO and LUMO energy levels could also be tuned effectively. The absorption spectra as well as electrochemical and photovoltaic properties of these polymers were investigated systematically. Some units exhibiting the same effect of bandgap lowering exhibited different effects on molecular energy levels of the polymers. For example, the TPZ unit can reduce the bandgap by lowering the LUMO energy level and elevating the HOMO level of the polymer, but the BT unit can lower the bandgap only by depressing the LUMO level. Since open-circuit voltage (Voc) of the heterojunction polymer solar cell is believed to be inversely proportional to the HOMO level of electron donor material, Voc of the devices based on H9, the copolymer of BDT and TPZ, was ca. 0.5 V lower than that of the device based on H7, the copolymer of BDT and BT. The effects of seven commonly used units on bandgap, molecular energy level, and photovoltaic properties of the BDT based polymers
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