Zhao Long
School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013, People's Republic of China.
ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Wollongong, New South Wales 2522, Australia.
R Soc Open Sci. 2018 Sep 26;5(9):181218. doi: 10.1098/rsos.181218. eCollection 2018 Sep.
This work investigates the effect of the second chromophore energy gap on charge generation in porphyrin-based di-chromophoric dye-sensitized solar cells (DSSCs). Three di-chromophoric porphyrin dyes (PorY, PorO and PorR) containing three organic chromophores with decreasing frontier orbital energy offsets, including a carbazole-triphenylamine chromophore (yellow, Y), a carbazole fused-thiophene chromophore (orange, O) or a carbazole-thiophene benzothiadiazole thiophene chromophore (red, R), were investigated using optical and electrochemical methods, steady-state photoluminescence and photovoltaic device characterization. Energy transfer from the organic chromophore to the porphyrin was suggested in PorY and PorO as the main charge generation mechanism in DSSCs using these di-chromophoric dyes. On the other hand, electron transfer from the photo-excited porphyrin to the organic chromophore as a competing pathway leading to the loss of photocurrent is suggested for PorR-sensitized solar cells. The latter pathway leading to a loss of photocurrent is due to the lower lying lowest unoccupied molecular orbital of the additional organic chromophore (R) and suggests the limitation of the current di-chromophoric approach to increase the overall efficiency of DSSCs.
本工作研究了第二发色团能隙对基于卟啉的双发色团染料敏化太阳能电池（DSSC）中电荷产生的影响。使用光学和电化学方法、稳态光致发光和光伏器件表征，研究了三种双发色团卟啉染料（PorY、PorO和PorR），它们包含三种前线轨道能量偏移逐渐减小的有机发色团，其中包括咔唑 - 三苯胺发色团（黄色，Y）、咔唑稠合噻吩发色团（橙色，O）或咔唑 - 噻吩苯并噻二唑噻吩发色团（红色，R）。在使用这些双发色团染料的DSSC中，PorY和PorO中从有机发色团到卟啉的能量转移被认为是主要的电荷产生机制。另一方面，对于PorR敏化的太阳能电池，建议从光激发的卟啉到有机发色团的电子转移是导致光电流损失的竞争途径。导致光电流损失的后一种途径是由于额外有机发色团（R）的最低未占据分子轨道较低，这表明当前双发色团方法在提高DSSC整体效率方面存在局限性。
