Effect of sandwiched YbCllayer thickness on exciton dynamics of Ybdoped CsPbClperovskite photodetectors.

Ybdoped CsPbClmetal halide perovskite photodetectors (PDs) in the structure of CsPbCl(50 nm)/YbCl(nm)/CsPbCl(50 nm), in whichranges from 10 to 40 nm corresponding to the molar ratio from 6.3% to 25.2%, are fabricated by thermal evaporation on Si/SiOsubstrate. Photoresponse from 350 to 980 nm have been achieved with the optimal responsivity () of 3959, 5425, 955 A Wfor the case of 20 nm YbClat the wavelength () 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 Yb. Moreover, the optimal YbClthickness of 20 nm can be ascribed to the balance between upconversion and concentration quenching of Yb. The influence of the YbCldoping on the CsPbClelectronic structure is investigated and downshifting and stabilization of valence band maximum (VBM) can be attributed to the p-type doping and counteracting effect of Yband Cl, respectively.