Organic-Inorganic Field Effect Transistor with SnI-based Perovskite Channel Layer using Vapor Phase Deposition Technique

摘要

High field-effect hole mobility of 0.28 cm~2/V·s (on/off ratio is more than 10~5, and threshold voltage is -3.2 V) in organic-inorganic layered perovskite film (C_6H_5C_2H_4NH_3)_2SnI_4 prepared by a vapor phase deposition technique have been demonstrated through the octadecyltrichlorosilane treatment of substrate. Previously, the (C_6H_5C_2H_4NH_3)_2PbI_4 films prepared on the octadecyltrichlorosilane-covered substrates using a vapor evaporation showed not only intense exciton absorption and photoluminescence in the optical spectroscopy but also excellent crystallinity and large grain structure in X-ray and atomic force microscopic studies. Especially, the (C_6H_5C_2H_4NH_3)_2PbI_4 structure in the region below few nm closed to the surface of octadecyltrichlorosilane monolayer was drastically improved in comparison with that on the non-covered substrate. Though our initial (C_6H_5C_2H_4NH_3)_2SnI_4 films via a same sequence of preparation of (C_6H_5C_2H_4NH_3)_2PbI_4 and octadecyltrichlorosilane monolayer did not show the field-effect properties because of a lack of spectral, structural, and morphological features. The unformation of favorable (C_6H_5C_2H_4NH_3)_2SnI_4 structure in the very thin region, that is very important for the field-effect transistors to transport electrons or holes, closed to the surface of non-covered SiO_2 dielectric layer was also one of the problems for no observation of them. By adding further optimization and development, such as deposition rale of perovskite, substrate heating during deposition, and tuning device architecture, with hydrophobic treatment, the vacuum-deposited (C_6H_5C_2H_4NH_3)_2SnI_4 have achieved above-described high performance in organic-inorganic hybrid transistors.