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 & DEG;C in situ annealingon Si/SiO2 substrates, and their photoresponse as wellas the morphology, structure, and photophysical properties are investigated.Wide spectrum photoresponse ranging from 350 to 980 nm has been achievedwith optimal responsivity (R) of 2364, 3766, and268 A/W at wavelengths (& lambda;) of 420, 680, and 980 nm, respectively.Such photoresponse behavior can be attributed to the parallel photoresponsefrom both CsPbCl3 and Si based on the UPS (ultravioletphotoelectron spectrometry) and XPS (X-ray photoelectron spectroscopy)results. Yb3+ doped CsPbCl3 PDs with the photosensinglayer structure of CsPbCl3 (50 nm)/YbCl3 (30nm)/CsPbCl3 (50 nm) have been prepared, and it was foundthat Yb3+ dopant is capable of realizing obviously shorterexciton lifetime at 420 nm, lower trap density, as well as remarkablyhigher carrier mobility due to the combined effects of energy transferfrom CsPbCl3 to Yb3+ and defect passivationfrom Yb3+, leading to remarkable improvement of the photoresponseperformance with optimal R (2709, 6340 and 3573A/W),noise equivalent power (NEP) (5.64 x 10(-7),2.51 x 10(-7), and 4.38 x 10(-7) W), and specific detectivity (D*) (1.84 x10(11), 3.24 x 10(11), and 1.5 x 10(11) cm Hz(1/2) W-1) compared to thoseof pristine CsPbCl3 at & lambda; of 420, 720, and 980 nm,respectively. Especially at the NIR & lambda; of 980 nm, 10-fold higher R is achieved after Yb3+ incorporation. The upconversionprocessing of Yb3+ can also be responsible for the enhancedwide spectrum photoresponse of Yb3+ doped CsPbCl3. Our study provides a practical way to realize wide spectrum perovskitePDs by simply connecting the perovskite to Si substrates by the Auelectrodes.