The polymer solar cell is composed of a blend active layer of a p-type conjugated polymer donor and a fullerene derivative or a non-fullerene n-type organic semiconductor acceptor sandwiched between a transparent conductive electrode and a metal electrode, Prominent advantages of processability, light weight, and the ability to be fabricated into flexible and translucent devices have been the focus of global energy research in recent years. Commercial applications of polymer solar cells require high efficiency, high stability of the device, and low cost This mainly depends on the development of photovoltaic materials.
Since the concept of bulk heterojunction was proposed by Alan J. Heeger et al in 1995, the research on photovoltaic materials and devices for polymer solar cells has been continuously developed. In the early stage of the research, the efficiency of the devices was very low and the research focus was mainly on improving Efficiency by increasing the device's short circuit current by designing and synthesizing narrowband systems, broad absorption and polymer donor photovoltaic materials with lower HOMO energy levels, and fullerene derivative acceptor photovoltaic materials with higher LUMO energy levels , Open circuit voltage and energy conversion efficiency.In recent years, with the development of narrow-bandgap non-fullerene n-type organic semiconductor acceptor photovoltaic materials and its absorption complementary wide bandgap polymer donor photovoltaic materials, the polymer solar cell The energy conversion efficiency has been rapidly improved, the efficiency of small area devices in the laboratory has exceeded 12 ~ 13% recently, reached the threshold that can be developed to practical application.So improving the stability and reducing the cost has become the practical application of polymer solar cells However, most of the currently reported highly efficient photovoltaic materials are complex in structure and difficult to synthesize, so it is difficult to meet the needs of commercial applications. Cost-effective photovoltaic materials will be a huge challenge for commercial applications of polymer solar cells.
Supported by the National Natural Science Foundation of China and the Chinese Academy of Sciences, researchers from the Chinese Academy of Sciences and the Chinese Academy of Sciences Institute of Chemistry Laboratory Key Laboratory of Organic Solid Li Yong Fang research group recently designed and synthesized a low cost and efficient polymer donor material PTQ10 (Molecular structure shown in Figure a) PTQ10 is a simple structure of the DA copolymer, wherein the thiophene ring as a donor unit, quinoxaline as a receptor unit in the quinoxaline introduced alkoxy side chain is to improve the polymerization Solubility and enhance light absorption, the introduction of double-fluorine atoms to reduce the polymer HOMO level and increase the hole mobility of the molecule can be cheap two-stage synthesis of raw materials (Figure c) and achieve nearly 90% of Total yield, making the cost of the material greatly reduced.More importantly, the use of PTQ10 as a donor, the structure is relatively simple n-type organic semiconductor IDIC (Figure a) is a polymer prepared by the polymer solar cells (see the device structure The maximum energy conversion efficiency of Fig. B) is 12.70%, and the efficiency of the reverse structure device reaches 12.13% (the efficiency confirmed by China Institute of Metrology is 12%). , The active layer thickness in the range of 100nm to 300nm can exceed 10% of the device efficiency, which is very conducive to large-scale preparation of the device.Compared with other highly efficient polymer donor photovoltaic materials reported in the literature more than 10% PTQ10 has the outstanding advantages of both yield and efficiency, both in the synthesis steps.
Considering the advantages of low cost, high efficiency and thickness insensitivity, the PTQ10 is highly promising as a polymer donor material in commercial applications of polymer solar cells. The work was published in the February 21 issue of Nat. Commun 2018, 9, 743).
