Application of small molecules based on a dithienogermole core in bulk heterojunction organic solar cells and perovskite solar cells

摘要

We report the synthesis and characterization of a dithienogermole(DTGe)based small molecule,named Ge-PO-2CN,as a donor material for bulk heterojunction(BHJ)organic solar cells(OSCs)and as a hole transport material(HTM)for dopant-free perovskite solar cells(PSCs).This molecule consists with a high planar and electron rich DTGe core as a central core unit and covalently linked with an electron rich phenoxazine group.Finally,it is end-capped with electron-deficient malononitrile group.This molecule was synthesized by a facile synthetic protocol,without using costly and complicated purification techniques.The Ge-PO-2CN compound has a suitable HOMO level with respect to the valence band of the perovskite absorber and the BHJ OSCs.The BHJ OSC device made with Ge-PO-2CN as the donor and PC71BM as an acceptor results in a power conversion efficiency(PCE)of 5.4%.Subsequently,the PSC with an active area of 1.02 cm~ constructed with dopant-free Ge-PO-2CN as an HTM achieved a PCE of up to 11.63%.