Synthesis And Properties Of Organic Photovoltaic Small Molecular Materials Based On Quinoxaline Derivatives

Compared with other materials, preparation and purification of small molecules photovoltaic materials which belong to environment-friendly photovoltaic materials are relatively easy. The latest reports of small organic molecules to the material efficiency of photovoltaic cells has exceeded 10%. This offers the possibility to commercialize small molecule material.Eight photovoltaic donor materials were designed and synthesized with quinoxaline derivatives as electron-accepter (A) units. On the quinoxaline electron-acceptor units (A), fluorine atoms are introduced. A fluorine atom has a strong electron withdrawing ability. Hence, fluorine atoms substitution can enhance the withdrawing capability of electron-acceptor units. Single bond, double bond, triple bond, cyano group respectively as a bridge bond introduced into triphenylamine (TPA) electron-donor unit (D), with different quinoxaline derivatives constitute of the D-A-D photovoltaic donor materials in this article.The structure of the as-synthesized 8 compounds were proved and confirmed by 'H-NMR and high resolution mass spectrometry. The HOMO and LUMO levels of the materials studied by density functional theory calculations can match the energy level of the acceptor material PC61BM well. The electrochemical and photovoltaic properties of the molecules have been extensively studied by UV-vis absorption spectroscopy and cyclic voltammetry. The organic solar cells with synthesized molecules as donor and PC61BM as acceptor were fabricated and tested.The following conclusions through the analysis of the data:(I) The materials after the introduction of a fluorine atom, an electron withdrawing inductive effect of fluorine atoms help to reduce the HOMO energy level of the material, and the material to obtain a higher open circuit voltage (Voc). (?) Series cyano materials have a high short-circuit current density (Jsc). When a cyano group was introduced into the D structure, cyano group electron withdrawing inductive effect increased the Jsc. (?) Series triple bond materials have a high Voc, the Voc of TPAFTQOL and TPAFFTQOL is 1.09 V,1.08 V. Series triple bond materials has better conjugation to increase the Voc of the materials. (?) Series cyano materials have high photoelectric conversion efficiency (PCE). the PCE of TPACQOL, TPAFCQOL, TPAFFCQOL was respectively 3.40%,3.61%,3.99%. From the data analysis is easy to see, TPAFCQOL has the best optoelectronic properties. From the results obtained, such materials have great potential in the future in-depth studies.