物理化学学报

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应用于染料敏化太阳能电池的基于染料R6的含有不同吸电子基团的有机染料的理论研究

魏珍, 李敏杰, 陆文聪   

  1. 上海大学理学院化学系, 上海 200444
  • 收稿日期:2019-05-30 修回日期:2019-07-16 录用日期:2019-07-25 发布日期:2019-07-31
  • 通讯作者: 李敏杰, 陆文聪 E-mail:minjieli@shu.edu.cn;wclu@shu.edu.cn
  • 基金资助:
    国家科技部“十三五”科技计划(2016YFB0700504),上海市自然科学基金(16ZR1411500)和上海市科学技术委员会(18520723500)资助项目

Theoretical Study of High-Efficiency Organic Dyes with Different Electron-Withdrawing Groups Based on R6 Toward Dye-Sensitized Solar Cells

Zhen Wei, Minjie Li, Wencong Lu   

  1. Department of Chemistry, College of Science, Shanghai University, Shanghai 200444, P. R. China
  • Received:2019-05-30 Revised:2019-07-16 Accepted:2019-07-25 Published:2019-07-31
  • Contact: Minjie Li, Wencong Lu E-mail:minjieli@shu.edu.cn;wclu@shu.edu.cn
  • Supported by:
    This project was supported by the National Key Research and Development Program of China (2016YFB0700504), Natural Science Foundation of Shanghai, China (16ZR1411500), Science and Technology Commission of Shanghai Municipality, China (18520723500).

摘要: 染料敏化太阳能电池(DSSCs)因具有低成本、制作简单、环境友好、效率高等优点,是目前最有希望代替传统化石能源的可再生能源。敏化剂作为DSSCs中最重要的组成部分之一,已经被研究了近30年。与金属染料相比,有机染料具有结构多样性,高摩尔吸光系数、性质易调控、环境友好等优点,成为比较有潜力的敏化剂。我们采用密度泛函理论(density functional theory,DFT)和含时密度泛函方法(time-dependent DFT,TD-DFT)研究了6个基于染料R6的D-A型有机染料的光电性质。并且系统的研究了DSSCs性能的相关参数包括几何结构、电子结构、吸收光谱、吸附能力、光捕获曲线(LHE)、理论短路电流密度(JscPred.)、理论开路电压(JscPred.)以及理论光电转换效率(PCE)。表明所有设计的染料都具有较高的PCE。其中染料RD1、2、4-6具有较好的共轭性,RD1-3表现出了较窄的带隙。染料RD1-3、5、6具有更强的光捕获能力,因为它们的吸收光谱覆盖了整个可见光区域,并扩展到近红外区,其最大吸光波长红移了,光捕获曲线拓宽了,理论短路电流也提高了。尤其突出的是染料RD1、2不仅表现出了更好的共轭性和更窄的带隙,还具有更好的光捕获能力。与染料R6相比,染料RD1、2的最大吸收波长红移了54 nm,其光捕获曲线(LHE)也拓宽了。值得一提的是,相比较于染料R6,染料RD1、2的短路电流密度平均提升了12%,使得染料的光电转换效率从染料R6的12.6%提升到了染料RD1、2的14.1%。因而,我们认为染料RD1、2有望成为染料敏化太阳能电池领域中潜在的高效纯有机染料候选物。我们的研究将为DSSCs有机染料的发现提供有效指导。

关键词: 非金属有机染料, DFT/TD-DFT, 光捕获能力, 光电性质, 光电转换效率

Abstract: Dye-sensitized solar cells (DSSCs) are the most promising alternatives to traditional fossil energy because of their advantages of low production cost, facile structure, relatively low environmental impact, relatively high photoelectronic absorption efficiency, and overall high efficiency. In addition, several studies on sensitizers as vital components have been conducted over the last three decades. Compared to metal dyes, metal-free organic dyes have been considered as promising candidates because of their simple fabrication, multiple structures, high molar absorption coefficients, easily tunable properties, and environmental friendliness. In this study, we systematically investigated the optoelectronic properties of six metal-free organic donor-acceptor dyes (RD1-6) derived from the known dye R6 by using the density functional theory (DFT) and time-dependent DFT methods. Cell performance parameters were discussed, including the geometrical and electronic structures, absorption spectrum, adsorption energy, light harvesting efficiency (LHE) curve, predictive short circuit current density (JscPred.), predictive open circuit voltage (VocPred.), and theoretical power conversion efficiency (PCE). Results revealed that all the designed dyes exhibited high theoretical PCE. In particular, dyes RD1, 2, and 4-6 showed greater conjugations, and dyes RD1-3 had smaller energy gaps than those of the reference dye. In addition, dyes RD1-3, 5, and 6 exhibited better light harvesting capacities that covered the entire visible region and extended to the near-infrared region with obviously red-shift maximum absorption wavelengths (λmax), wider LHE curves, and higher JscPred. as compared to the reference dye. It was critical that dyes RD1 and 2 not only have greater conjugations and narrow band gaps but also good light harvesting capacities with more than 56-nm red-shift maximum absorption wavelengths and broadened LHE curves than those of the reference dye. Notably, mainly because of an average increment of 12.0% of JscPred., a remarkable increment of the theoretical power conversion efficiency was observed from 12.6% for dye R6 to 14.1% for dyes RD1 and 2. Thus, dyes RD1 and 2 exhibited superior cell performances and could be promising sensitizer candidates for highly efficient DSSCs. These results could be used to guide effective synthetic efforts in the discovery of efficient metal-free organic dye sensitizers in DSSCs.

Key words: Metal-free organic dyes, DFT/TD-DFT, Light-harvesting ability, Optoelectronic property, Power conversion efficiency

MSC2000: 

  • O641