Direct-band gap, solution-processed 2D layered perovskites for flexible photodetectors

The two-dimensional (2D) halide perovskites have recently drawn significant interest due to their tunable optoelectronic properties and high-power conversion efficiencies in photovoltaic applications. Here we present the synthesis of the solution processed 2D layered organo-halide (CH3(CH2)3NH3)2(CH3NH3)n-1PbnI3n+1 (n = 4) perovskites and the fabrication of heterostructure flexible photodetector (PD) devices on polyimide (PI) substrates using the additively manufactured process of ink-jet printing. The devices were found to be photoresponsive to broadband incoming radiation in the visible regime. A high ON/OFF ratio ~ 2.3×10³ and response times on the rising and falling edges, $\tau_{rise}$ and $\tau_{fall}$ were determined to be ~ 24 ms and ~ 65 ms, respectively. Finally, in this work we also report on the first strain dependent measurements on ink-jet printed perovskite PDs, where the photocurrent $I_{p}$ decreased by only 27% upon bending with radius of curvature of ~0.262 cm⁻¹, The flexible, ink-jet printed 2D perovskite heterostructure PDs have significant potential for optoelectronic devices which can enable broad possibilities given the compositional tunability and versatility of the 2D organohalide perovskites.