Thermally Evaporated CsPbCl₃ Perovskite on Si/SiO₂ with Wide Spectrum Photoresponse from Ultraviolet (UV) to Near-Infrared (NIR)

CsPbCl 3 metal halide perovskite photodetectors (PDs) are prepared via thermal evaporation and 75 °C in situ annealing on Si/SiO 2 substrates, and their photoresponse as well as the morphology, structure, and photophysical properties are investigated. Wide spectrum photoresponse ranging from 350 to 980 nm has been achieved with optimal responsivity ( R ) of 2364, 3766, and 268 A/W at wavelengths (λ) of 420, 680, and 980 nm, respectively. Such photoresponse behavior can be attributed to the parallel photoresponse from both CsPbCl 3 and Si based on the UPS (ultraviolet photoelectron spectrometry) and XPS (X-ray photoelectron spectroscopy) results. Yb 3+ doped CsPbCl 3 PDs with the photosensing layer structure of CsPbCl 3 (50 nm)/YbCl 3 (30 nm)/CsPbCl 3 (50 nm) have been prepared, and it was found that Yb 3+ dopant is capable of realizing obviously shorter exciton lifetime at 420 nm, lower trap density, as well as remarkably higher carrier mobility due to the combined effects of energy transfer from CsPbCl 3 to Yb 3+ and defect passivation from Yb 3+, leading to remarkable improvement of the photoresponse performance with optimal R (2709, 6340 and 3573A/W), noise equivalent power (NEP) (5.64 × 10 –7, 2.51 × 10 –7, and 4.38 × 10 –7 W), and specific detectivity ( D *) (1.84 × 10 11, 3.24 × 10 11, and 1.5 × 10 11 cm Hz 1/2 W –1 ) compared to those of pristine CsPbCl 3 at λ of 420, 720, and 980 nm, respectively. Especially at the NIR λ of 980 nm, 10-fold higher R is achieved after Yb 3+ incorporation. The upconversion processing of Yb 3+ can also be responsible for the enhanced wide spectrum photoresponse of Yb 3+ doped CsPbCl 3 . Our study provides a practical way to realize wide spectrum perovskite PDs by simply connecting the perovskite to Si substrates by the Au electrodes.