共轭非平面D-A型稠环的快捷合成与光伏应用

Solving the energy and environmental crisis problem is an urgent task for ensuring sustainable development. Solar energy is one of the most useful alternative sustainable energy sources as its abundance is “virtually unlimited” and free. Among the available technologies, dye sensitized solar cells (DSSCs), are a front runner among new solar cell technologies owing to their low production cost and efficiency, which make them a promising alternative for certain applications. The most important part of DSSCs is the photosensitizer. Organic dyes have demonstrated great potential in both design flexibility and amenability to optimization in terms of device performances. However, most of organic dyes are easy to form intermolecular aggregation decreasing the photoelectric conversion efficiency. Meanwhile, these dyes tend to contain many different groups which complicates synthesis and purification and ultimately increases dye cost which is an issue for device scaling and commercialization. In response to these disadvantages, our project is aim to get some high efficiency organic dyes based on novel donor-acceptor type fused aromatic cycles, which is easy to synthesis. And, we design a series of organic dyes based these fused aromatic cycles, which with these advantages: high value of molar extinction coefficient, absorbing the maximum solar spectrum, suppression of dye aggregation. By testing the photoelectric conversion efficiency of the cell, the dual relationship between the molecular structure of the dyes and the performance of the cell will be studied and discussed in detail. This design might open up the promising possibility to prepare novel organic dye for an enhanced light-current conversion and provide new ideas to improve photoelectric conversion efficiency of dye-sensitized solar cells. The system of its mechanism of action study, completed projects can provide some important methods, theoretical basis and technical support for highly efficient photosensitizers.

为解决日趋严峻的能源短缺和环境问题，成本低廉、效率可观的有机染料敏化太阳电池的开发成为了新能源研究的热点之一。但是，有机染料大都存在着以下缺点：1）光响应能力和抑制聚集能力偏弱，光电转换效率有待进一步提高；2）合成路线冗长，生产成本高。基于此，本申请项目拟采用碳氢活化直接芳基化反应为关键合成步骤，以噻吩-3-乙酸乙酯与4,7-二溴苯并噻二唑等为原料，希望简捷快速地合成一系列具有抑制聚集功能、可增强光响应能力的D-A型稠环；并将其用于染料敏化太阳能电池中，研究结构与光伏性能的内在联系。总之，本项目的执行将获得若干合成简单、光电转换效率高的基于共轭非共平面D-A型稠环的有机染料，并为高性能有机半导体的快速合成和应用、提高染料敏化太阳能电池的光电转换效率提供重要的设计思路和理论依据。

随着近年来化石资源的日益枯竭以及环境污染问题的日趋严重，多种可持续清洁能源技术被人们开发出来。染料敏化太阳能电池(dye-sensitized solar cells，简称DSCs)因制备工艺简单、光电转化率可观、材料来源丰富等优点成为了研究热点。染料敏化剂是DSCs的核心部分，负责吸收太阳光子生成电子并将电子传输至光阳极，直接影响DSCs的光电转换效率。虽然有机染料敏化的DSCs光电转换效率已经超过了14%，但是高性能、低成本的高效染料仍然较为少见。因此设计和开发合成简便、成本低廉的高性能有机染料敏化剂有望推动高性价比DSCs的诞生和大规模应用。.本项目申报时设计了共轭非平面D-A型稠环，但在关键的合成步骤上设计失误，导致原设计的最终产物无法获得。通过调整思路，高效简捷地合成了基于并吲哚结构的“准D-A型”和D-A型不对称稠环，设计了五个系列小分子材料用于染敏电池或钙钛矿太阳能电池。.我们基于吡咯并吲哚环构筑了第一系列5个目标染料。相较于传统的D-π-A结构染料，由于π-D-A结构染料具有更高的消光系数有利于光电流的提高，获得更好的光伏表现。同时，在π结构上引入烷基链可以轻微的实现最大吸收波长的红移，并提高染料抑制聚集的能力。最终化合物QD-05实现了5.70%的光电转换效率，可达相同条件下经典染料N719的80%。.基于噻吩并吲哚环构筑了第二系列7个目标染料。π-D-A结构在这一系列染料中获得了更好的光伏表现；同时，π结构对染料最终吸光范围有明显影响，但是过于平面化的π结构会引起染料的H-聚集，从而不利于光伏性能的提高。噻吩并吲哚环氮原子上烷基链的长度对光伏表现有着较大的影响，增长烷基链有利于染料溶解度的提升，摩尔消光系数的提高，从而有利于较高光电流的获得。.基于茚并吲哚环构筑了第三系列3个D-D-π-A型目标染料。D-D-π-A结构染料的第二个给体决定了吸光范围，对器件光响应范围起着重要作用。.因时间关系，第四、五系列共十种新材料，尚有部分材料正在纯化中，待纯化完成，我们将及时完成它们相应的光物理、电化学、光伏性能的测试。.