Lead-free and amorphous organic-inorganic hybrid materials for photovoltaic applications: mesoscopic CH3NH3MnI3/TiO2 heterojunction

As one type of organic-inorganic hybrid material, APbX(3) organic-inorganic lead perovskite materials have attracted considerable attention in optoelectronic applications. Although organic-inorganic lead perovskites possess high solar-to-electrical conversion efficiency, the toxic Pb in organic-inorganic lead perovskites is expected to cause environmental pollution in future mass applications. Thus, exploiting Pb-free organic-inorganic hybrid materials is urgently needed. In this study, a lead-free and amorphous CH3NH3MnI3 (a-MAMnI(3)) thin film was prepared by spin coating a mixed MnI2 and MAI precursor solution on an electronic transport layer (ETL)-TiO2. A mesoscopic a-MAMnI(3)/TiO2 heterojunction was formed by filling the mesoporous TiO2 layer with MAMnI(3). The architecture of the optoelectronic device is FTO/ETL-TiO2/a-MAMnI(3)/Spiro-MeOTAD/Ag. The photovoltage of the optoelectronic device based on the mesoscopic a-MAMnI(3)/TiO2 heterojunction reached 300 mV under AM1.5, 100 mW cm(-2) simulated illumination. The evident photoresponse was observed at 530 nm green light. The test with 2000 s on/off cycling indicated the good stability and repeatability of the device. The findings pave a way for realizing Pb-free and amorphous organic-inorganic hybrid materials applied to optoelectronic logic devices, photodetectors, and optical memory devices.