Effect of sandwiched YbCl3 layer thickness on exciton dynamics of Yb3+ doped CsPbCl3 perovskite photodetectors

Abstract

Abstract Yb3+ doped CsPbCl3 metal halide perovskite photodetectors (PDs) in the structure of CsPbCl3(50 nm)/YbCl3(x nm)/CsPbCl3(50 nm), in which x ranges from 10 to 40 nm corresponding to the molar ratio from 6.3% to 25.2%, are fabricated by thermal evaporation on Si/SiO2 substrate. Photoresponse from 350 to 980 nm have been achieved with the optimal responsivity (R) of 3959, 5425, 955 A W−1 for the case of 20 nm YbCl3 at the wavelength (λ) of 420, 680 and 980 nm, respectively. A series of photophysical and electrical characterization has been performed and it is found that the remarkably improved photoresponse originates from the combining effects of upconversion and defects passivation from Yb3+. Moreover, the optimal YbCl3 thickness of 20 nm can be ascribed to the balance between upconversion and concentration quenching of Yb3+. The influence of the YbCl3 doping on the CsPbCl3 electronic structure is investigated and downshifting and stabilization of valence band maximum (VBM) can be attributed to the p-type doping and counteracting effect of Yb3+ and Cl−, respectively.