Synthesis And Properties Of Small-Molecule Non-Fullerene Electron Acceptor Materials Based On Thienoisobenzopyran

Non-fullerene small molecule receptors?NF-SMAs?have received extensive attention because of their advantages such as easy-adjustable absorption spectra and electronic energy levels,good active layer morphology,and defined molecular structure.This paper focuses on the research status and progress of A-D-A NF-SMAs with fused ring core and non-fused ring core.Aiming at the current problems of NF-SMAs,this paper designs and synthesizes A-D-A type NF-SMAs based on thienoisobenzopyran,and systematically studies the relationship between material structure and performance.The specific research of this paper is as follows:1. Design and synthesis the NF-SMAs of BTPT-BR and BTPT-BRCN,and use polymer PTB7-Th as the donor material to produce organic solar cells?OSCs?. The study found that the optical band gap?E_g?of BTPT-BR and BTPT-BRCN were 1.58 and 1.49e V,respectively.Compared with BTPT-BRCN,the energy levels of BTPT-BR and PTB7-Th are more matched,and the absorption spectrum is more complementary.The external quantum efficiency?EQE?of OSCs based on PTB7-Th:BTPT-BR reached more than 65%.Also,the electron-hole mobility of BTPT-BR is higher and more balanced,and the device exhibits higher short-circuit current(J_sc)and fill factor?FF?.OSCs based on PTB7-Th:BTPT-BR achieved a maximum energy conversion efficiency?PCE?of 6.47%with a high open circuit voltage(V_oc)of 1.03 V.OSCs based on PTB7-Th:BTPT-BRCN achieved a PCE of 3.36%with a V_ocof 0.95 V.2. Design and synthesis the NF-SMAs of TT2TC-2Cl and TT2TC-2D,and the molecular absorption and energy level were adjusted by connecting different end groups. The introduction of thiophene units in NF-SMAs prolongs the molecular conjugation,strengthens the?-?stacking,and broadens the absorption range.The study found that TT2TC-2Cl showed broad and strong ultraviolet-visible absorption,with E_gof 1.43 e V,respectively.A study of the electrochemical performance of TT2TC-2Cl and TT2TC-2D revealed that their highest occupied molecular orbital?HOMO?energy levels were-5.26and-5.42 e V,and their lowest unoccupied molecular orbital?LUMO?energy levels were-3.58 and-3.58 e V.OSCs based on PTB7-Th:TT2TC-2Cl achieved a maximum PCE of6.47%with a V_ocof 0.78 V.OSCs based on PTB7-Th:BTPT-BRCN achieved a PCE of2.43%with a V_ocof 1.14 V.