Progress in the design and application of new pi molecular materials

The development of new organic pi molecular materials and their application in solar cells, field-effect transistors, light-emitting diodes and other fields are important research contents of organic optoelectronics With the support of the strategic class B leading science and technology program of CAS, Zhu Xiaozhang, a research team member of the Key Laboratory of all Institute of organic solids of CAS, found that thiophene [3,4-b] and thiophene (TBT) (J am Chem SOC 2015, 137, 10357-10366) with quinone type enhancement effect may be widely used in the field of organic optoelectronics In recent years, they have developed a series of new functional pi molecular materials (J am Chem SOC 2015, 137, 11294-11302; J am Chem SOC 2014, 136, 16176-16184; J mater Chem A 2015, 3, 11194-11198) on the basis of TBT selective functionalization, showing good application prospects in field effect transistors and solar cells Compared with p-type organic semiconductors, the development of air stable n-type organic semiconductors lags behind significantly Quinone oligothiophene is a typical n-type semiconductor material, but in the past ten years, its electron mobility has not exceeded 1.0 cm2 V-1 s-1, which may be due to its one-dimensional molecular structure limiting Pi Pi stacking A two-dimensional PI extended quinone thiophene 2dqtt was designed and synthesized and the electron mobility of 3.0 cm2 V-1 S-1 was obtained O n this basis, researchers continue to conduct in-depth research on the regional chemistry of the molecular system and the influence of alkyl chain on the film stacking 2dqtt-o-b with mobility and switch ratio of 5.2cm2 v-1s-1 and 106 respectively has been developed, which is the highest value reported for solution processing and air stable n-type organic small molecular thin film transistors Relevant results are published in adv mater 2016, 28, 8456-8462 Two dimensional PI extended quinone thiophene compounds and their electronic mobility in the field of solar cells, researchers based on two classical strategies of D-A structure and quinonization, put forward a new idea of "enhancing quinone resonance of D-A system" design and construction of organic photovoltaic materials A new type of small molecule donor material stb-n was designed by introducing the quinonylated TBT functional unit This kind of material has the electronic structure matching with PCBM Through the side chain control, the photoelectric conversion efficiency of small molecule donor material stb-3 is as high as 9.26%, which proves the feasibility of this idea for the design of small molecule donor material The relevant results are published in J mater Chem A 2016, 4, 17354-17362 At the same time, based on the study of small molecular donor materials, the researchers designed a new kind of non fullerene receptor material att-1 by introducing electron pulling groups on TBT and rhodanine and reducing LUMO energy levels of compounds This material has a wide spectrum absorption in the range of 500-800 nm Through matching with the widely used donor material ptb7 th, the photoelectric conversion efficiency is up to 10.07% The relevant results are published on J am Chem SOC 2016, 138, 15523-15526 This study shows that the strategy of "enhancing the quinone resonance of D-A system" has important guiding significance for the design of organic photovoltaic donor / acceptor materials A new solar donor (a) and acceptor (b) materials based on TBT