Tailoring heterojunction energetics for a high-performance self-powered halide perovskite photodetector without charge transport layers

Abstract

Self-powered photodetectors (PDs) offer significant advantages for low-power and portable optoelectronic applications by eliminating the need for external power sources. However, conventional architectures typically rely on charge transport layers (CTLs), which add fabrication complexity, increase material cost, and often compromise long-term device stability. In this work, we demonstrate a high-performance self-powered PD through tailoring heterojunction energetics in a CTL-free all-inorganic perovskite/perovskite heterojunction composed of Bi-doped CsPbBr₃ and Cs₂AgBiBr₆. The engineered type-II band alignment and optimized interfacial energetics create an intrinsic built-in potential, facilitating efficient charge separation and directional carrier transport without external bias. Steady-state and time-resolved photoluminescence (TRPL) studies reveal high carrier mobility and suppressed recombination dynamics, depicting an efficient charge extraction across the junction. The CTL-free device achieves a high responsivity of ∼0.25 A W⁻¹ and high detectivity of ∼2.8 × 10¹² Jones under low light intensity, demonstrating its ability to operate efficiently with a simplified architecture, while a reference device incorporating a TiO₂ electron transport layer reaches ∼8.8 × 10¹² Jones, attributed to improved energy-level alignment. These findings demonstrate that CTL-free perovskite heterojunctions can enable scalable, low-cost, and stable self-powered photodetectors, offering a promising route for next-generation optoelectronic devices with simplified architectures.