Carrier photodynamics in 2D perovskites with solution-processed silver and graphene contacts for bendable optoelectronics

Abstract

Abstract Silver (Ag) and graphene (Gr) inks have been engineered to serve as efficient electrical contacts for solution-processed two-dimensional (2D) organo-halide (CH3(CH2)3NH3)2(CH3NH3) n−1Pb n I3n+1 (n = 4) layered perovskites, where all inkjet-printed heterostructure photodetectors (PDs) were fabricated on polyimide (PI) substrates. To date, limited studies exist that compare multiple contacts to enable high-performance engineered contacts to 2D perovskites. Moreover, of these few reports, such studies have examined contacts deposited using vapor-based techniques that are time-consuming and require expensive, specialized deposition equipment. In this work, we report on the inkjet printed, direct contact study of solution-processed, 2D perovskite-based PDs formed on flexible PI substrates. Solution processing offers a cost-effective, expedient route for inkjet printing Gr and Ag using a dispersion chemistry developed in this work that is compatible with the underlying 2D perovskite layer to construct the PDs. The wavelength λ-dependent photocurrent I p peaked at λ ~ 630 nm for both PDs, consistent with the bandgap E g ~ 1.96 eV for our semiconducting 2D perovskite absorber layer. The external quantum efficiency was determined to be 103% for Ag-perovskite PDs, where strain-dependent bending tests were also conducted to reveal the opto-mechanical modulation of the photocurrent in our devices.