以咔唑为π-桥的D-π-A型有机染料分子的合成与性能  

The synthesis and properties of D-π-A organic dyes based on carbazole unit as π-bridge

作　　者：曹威[1] 方曼曼[1] 刘凡[1] 王金凤[1] 钟成[1] 李振[1] 陈兴国[1] 梅安意 韩宏伟[2] 

机构地区：[1]有机高分子光电功能材料湖北省重点实验室,武汉大学化学与分子科学学院,武汉430072 [2]华中科技大学武汉光电国家实验室(筹),武汉430074

出　　处：《中国科学：化学》2016年第5期496-509,共14页SCIENTIA SINICA Chimica

基　　金：国家自然科学基金(编号:51173138)资助项目

摘　　要：本文分别以三苯胺、N-苯基咔唑和吲哚[3,2,1-jk]咔唑为给体,选择3,6-和2,7-位连接的咔唑为π-桥与氰基乙酸受体键连合成了两个系列共6个D-π-A型染料分子,研究了以它们为光敏剂的染料敏化太阳能电池器件的光伏性能.通过对比发现,给体单元相同的染料分子,以2,7-位连接的咔唑为π-桥时其共轭骨架的π-电子离域比3,6-位连接更好,因而其分子内电荷转移吸收明显变宽并增强,表现出更好的分子捕光能力,相应电池器件的短路电流密度(J_(sc))更大,展示了更高的光电转换效率;当π-桥相同时,给体单元由三苯胺依次变换为N-苯基咔唑和吲哚[3,2,1-jk]咔唑后,伴随苯环之间的直接键连其分子共平面性增强,氮原子上孤对电子参与共轭的程度增大,这虽有利于给体单元共轭骨架的π-电子离域,但会导致氮原子孤对电子参与的分子内推拉电子效应减弱,影响体系对太阳光的吸收利用,同时刚性共平面骨架加剧了分子间π-π堆积,引起染料聚集而加速载流子复合,从而影响其电池器件的开路电压(V_(oc))和J_(sc),不利于光伏性能的提升.In this work, triphenylamine, N-phenyl-9H-carbazole and indolo[3,2,1-jk]carbazole unit as a donor, 3,6-carbazole or 2,7-carbazole unit as a π-bridge, and cyanoacrylic acid as an acceptor have been chosen to construct two series of six D-π-A metal-free organic dyes（CL-Ⅰ–CL-Ⅲ and CL-Ⅳ–CL-Ⅵ）. The corresponding dye sensitized solar cell（DSSC） devices based on these dyes have been fabricated and the photovoltaic performances have been studied. It is found that the dyes containing 2,7-carbazole unit as π-bridge shows better photovoltaic performances than that of the counterpart using 3,6-carbazole unit as π-bridge with the same donor, which can be attributed to the better conjugation of 2,7-carbazole unit as π-bridge than 3,6-carbazole unit in the similar molecular skeleton, thus leading to stronger intramolecular charge transition effect and better light hunting ability. As for a series of the dyes with same π-bridge, after changing the donor from triphenylamine to N-phenyl-9H-carbazole, and then to indolo[3,2,1-jk]carbazole the molecular coplanarity has been strengthened due to the direct connection among the phenyl rings, which results in more efficient conjugation of lone pair electron of N atom in the conjugation skeleton of donor unit. However, it weakens the intramolecular push-pull electron effect, which is unfavorable to the utility of sun light. Moreover, the enhancement of the molecular coplanarity can greatly strengthen the intermolecular π-π interaction that intensifies the dye aggregations and quickens the combination of the charge carriers, which is not conducive to the improvement of photovoltaic performances. Thus, the open circuit voltage and short circuit current density of the DSSC devices is getting worse in a general trend.

关 键 词：有机染料 D-π-A结构 染料敏化太阳能电池 光伏性能 结构性能关系 

分 类 号：O626[理学—有机化学]