Effect of sandwiched YbCl3layer thickness on exciton dynamics of Yb3+doped CsPbCl3perovskite photodetectors

Abstract

Yb³⁺doped CsPbCl₃metal halide perovskite photodetectors (PDs) in the structure of CsPbCl₃(50 nm)/YbCl₃(xnm)/CsPbCl₃(50 nm), in whichxranges from 10 to 40 nm corresponding to the molar ratio from 6.3% to 25.2%, are fabricated by thermal evaporation on Si/SiO₂substrate. Photoresponse from 350 to 980 nm have been achieved with the optimal responsivity (R) of 3959, 5425, 955 A W^-1for the case of 20 nm YbCl₃at 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 YbCl₃thickness of 20 nm can be ascribed to the balance between upconversion and concentration quenching of Yb³⁺. The influence of the YbCl₃doping on the CsPbCl₃electronic 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.

Keywords: Yb3+ upconversion; electronic structure; perovskite; photodetector; wide spectrum.