Research Progress in Organic Optoelectronic Devices Based on Large π Conjugated Molecules Tetraphenyldibenzoperiflanthene and Diindenoperylene

In recent years, the application of organic semiconductors has promoted the rapid development of organic optoelectronics. Compared with polymer semiconductor devices, small-molecule semiconductor devices have better reproducibility and controllability, more diversified fabrication processes, simpler interface regulation and clearer mechanism. However, small-molecule semiconductors have higher requirement in equipment and process, especially the process parameters exert a significant influence on the molecular aggregation state and orientation in the film. Currently the disadvantages of small-molecule semiconductor materials are as follows: (1) it is difficult to obtain thin films with highly ordered molecular arrangement via conventional fabrication process; (2) small-molecule semiconductors which can be fabricated by evaporation and solution- processing are relatively lack; (3) the optical absorption range is relatively narrow and the exciton diffusion length is shorter. Small molecules of tetraphenyldibenzoperiflanthene (DBP) reported firstly in 2009 and its derivative diindenoperylene (DIP) show excellent photoelectronic properties. DBP demonstrates strong visible absorption, bipolar transport, high hole-mobility, strong trend of horizontal molecular orientation, high light- and thermal-stability. DIP indicates bipolar transport, perpendicular molecular orientation, and apparent crystallinity. Therefore, DBP and DIP have attracted more and more scientists' attention. In recent years, researchers have mainly tried to improve the performance of organic optoelectronic devices based on DBP and DIP by equipment modification, fabrication process, device structure, and material matching and so on. DBP and DIP have been efficiently applied in organic solar cells (OSC), organic light emitting diodes (OLED), and organic field effect transistors (OFET). The photocurrent and filling factor of DBP photovoltaic cells were increased by thermal annealing and solvent vapor annealing, and higher open-circuit voltage was obtained by using DBP as acceptor or matching DBP donor with non-fullerene acceptor. For DBP-based OLED and OFET, the correlation between device performance and the transport characteristics of buffer layers, the emitting layer structure, the substrate temperature, and the channel length are mainly studied. With regard to the DIP thin films, in recent years the methods of oblique gra-zing angle deposition, temperature control, annealing process, and molecular template have been introduced into the regulation of molecular orie-ntation in thin films. The OSCs based on DIP donor or DIP receptor were prepared due to the bipolar transport of DIP and achieved high efficiency of 5.8%. In addition, the molecular arrangement of other semiconductors is guided by the crystalline DIP to increase the mobility of the OFETs. This paper systematically reviews the DBP and DIP properties and the important research progress in many kinds of organic optoelectronic devices. Finally, the development tendency in the future of organic optoelectronic devices based on DBP and DIP is prospected, hoping to provide a reference for the molecular design and application of such type of small molecular semiconductors. © 2020, Materials Review Magazine. All right reserved.