Sputtered SnOx electron transport layer for inverted perovskite photodetectors-An alternative to atomic layer deposition

Abstract

Perovskite photodetectors (PePDs) represent a promising extension of perovskite solar cells (PSCs), sharing the device architecture but targeting distinct performance metrics. While PSCs prioritize high power conversion efficiency and operational stability, PePDs require low dark-current, high responsivity, detectivity, and fast response. These traits depend strongly on the transport layers, which govern interfacial recombination and carrier extraction dynamics. Tin-oxide (SnOx), widely employed as an electron transport layer in PSCs due to its transparency, energy-level alignment, and chemical stability, is an attractive candidate for PePDs. Traditionally, SnOx is deposited via atomic layer deposition, which offers excellent conformality and thickness control but suffers from high precursor and processing gas costs and low throughput thus limiting its scalability. In this work, we explore magnetron sputtering as a scalable alternative. However, conventional sputtering can damage underlying layers through ultraviolet radiation and high-energy particle bombardment. To address this, we developed a soft-sputtering protocol that enables SnOx deposition on inverted perovskite devices while preserving the integrity of the underlying layers. Devices fabricated with soft-sputtered SnOx exhibit a low-leakage current of 10-8 A cm-2 at-0.5 V, a detectivity of up to 1012 Jones, and fast response times of less than 2 mu s for an active area of 0.125 cm2.