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

CsPbCl3 metal halide perovskite photodetectors (PDs) are prepared via thermal evaporation and 75 °C in situ annealing on Si/SiO2 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 CsPbCl3 and Si based on the UPS (ultraviolet photoelectron spectrometry) and XPS (X-ray photoelectron spectroscopy) results. Yb3+ doped CsPbCl3 PDs with the photosensing layer structure of CsPbCl3 (50 nm)/YbCl3 (30 nm)/CsPbCl3 (50 nm) have been prepared, and it was found that Yb3+ 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 CsPbCl3 to Yb3+ and defect passivation from Yb3+, 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 × 1011, 3.24 × 1011, and 1.5 × 1011 cm Hz1/2 W–1) compared to those of pristine CsPbCl3 at λ of 420, 720, and 980 nm, respectively. Especially at the NIR λ of 980 nm, 10-fold higher R is achieved after Yb3+ incorporation. The upconversion processing of Yb3+ can also be responsible for the enhanced wide spectrum photoresponse of Yb3+ doped CsPbCl3. Our study provides a practical way to realize wide spectrum perovskite PDs by simply connecting the perovskite to Si substrates by the Au electrodes.