Ultrasensitive Sn-Pb perovskite photodetector for monolithic near-infrared imaging

Tin-lead (Sn-Pb) perovskites exhibit great potential in application of near-infrared (NIR) photodetectors due to their narrow optical bandgap of ∼1.2 eV. However, their inferior stability caused by the oxidation of Sn²⁺ to Sn⁴⁺ and the film defects still limit the device performance. Herein, we introduced ammonium chloride (NH₄Cl) into the precursor ink to regulate the crystallization dynamics of Sn-Pb perovskite film, suppress the oxidation of Sn²⁺, and passivate the associated defects. Consequently, the photodetector achieves a wide spectral response spanning 300–1100 nm, along with an impressive specific detectivity of 1.42 × 10¹¹ Jones, a linear dynamic range of 173 dB, and an ultrafast rise/fall time of 377/860 ns. The optimal device exhibits a negligible performance attenuation after stressed under continuous on/off NIR radiation at 980 nm for 120 min. Furthermore, we integrate the photodetector with a commercial transistor readout circuit for imaging, which delivers an outstanding imaging quality under NIR radiation with a spatial resolution of 1.67 lp mm⁻¹ . This work paves an avenue for the development of advanced NIR imager and the commercialization of Sn-Pb perovskite semiconductors for intelligent consumer electronics.