# Monolithic Integration of Redox-Stable Sn–Pb Halide Perovskite Single-Crystalline Films for Durable Near-Infrared Photodetection

## TL;DR

A new low-temperature method produces stable tin-lead perovskite films for efficient and durable near-infrared photodetectors.

## Contribution

A coordination-engineered crystallization strategy enables redox-stable, low-temperature growth of Sn–Pb perovskite single-crystal films.

## Key findings

- Micrometer-thick Sn–Pb single-crystal films are grown at ≤40 °C with high structural and compositional integrity.
- Photodetectors using these films achieve 73.8% external quantum efficiency and stable performance over 25,000 cycles.
- The films have ultralow trap densities (~3.98 × 1012 cm−3) and high specific detectivity (3.6 × 1012 Jones).

## Abstract

Cosolvent-coordinated crystallization at ≤40 °C enables planar integration of micrometer-thick Sn–Pb single-crystal films with high structural and composition integrity.A tailored solvent matrix yields thickness-tunable single-crystal thin films with ultralow trap densities (~3.98 × 1012 cm−3) and robust ambient stability.Integrated near-infrared photodetectors achieve 73.8% EQE, 0.51 A W−1 responsivity, 3.6 × 1012 Jones specific detectivity, and stable performance over 25,000 cycles.

Cosolvent-coordinated crystallization at ≤40 °C enables planar integration of micrometer-thick Sn–Pb single-crystal films with high structural and composition integrity.

A tailored solvent matrix yields thickness-tunable single-crystal thin films with ultralow trap densities (~3.98 × 1012 cm−3) and robust ambient stability.

Integrated near-infrared photodetectors achieve 73.8% EQE, 0.51 A W−1 responsivity, 3.6 × 1012 Jones specific detectivity, and stable performance over 25,000 cycles.

The online version contains supplementary material available at 10.1007/s40820-025-01991-y.

Tin–lead (Sn–Pb) halide perovskite single crystals combine narrow bandgaps, long carrier diffusion lengths, and low trap densities, positioning them as ideal candidates for near-infrared (NIR) optoelectronics. However, conventional growth strategies rely on bulk crystallization at elevated temperatures, leading to uncontrolled nucleation, Sn2+ oxidation, and poor compatibility with planar integration. Here, we develop a coordination-engineered crystallization strategy that enables direct, low-temperature growth of micrometer-thick Sn–Pb single-crystal thin films on device-compatible substrates. By modulating metal–solvent coordination strength using a low-donor number cosolvent system, we delineate a narrow processing window that stabilizes precursor speciation, lowers the nucleation barrier, and guides directional crystal growth under mild thermal conditions (< 40 °C). The resulting crystal films exhibit smooth morphology, high crystallinity, compositional uniformity, and ultralow trap densities (~ 3.98 × 1012 cm−3). When integrated into NIR photodetectors, these films deliver high responsivity (0.51 A W−1 at 900 nm), specific detectivity up to 3.6 × 1012 Jones, fast response (~ 188 μs), and > 25,000 cycles of ambient operational stability. This approach establishes a scalable platform for redox-stable, low-temperature growth of Sn–Pb perovskite crystal films and expands the processing–structure–function landscape for next-generation infrared optoelectronics.

The online version contains supplementary material available at 10.1007/s40820-025-01991-y.