Enhanced Photostability and Photoluminescence of PbI₂ via Constructing Type‐I Heterostructure with ZnO

Abstract

Improving the stability of lead iodide (PbI2), especially photostability, is in crucial demand for the realization of application‐level optoelectronic devices. In this regard, deposition of organic polymers on PbI2 as a protective layer is a common strategy to improve its stability, but polymers with low thermal conductivity generally cannot produce the desired effect. Herein, a novel strategy is proposed for improving the photostability of PbI2 at different excitation wavelengths, including 320, 405, and 532 nm, via constructing type‐I heterostructure with ZnO with high thermal conductivity. In addition, due to the type‐I band alignment between PbI2 and ZnO, the photogenerated carriers in ZnO can be transferred to PbI2, resulting in a nearly eightfold photoluminescence enhancement of PbI2 under 320 nm laser excitation. The ZnO as a protective layer forming type‐I heterostructure is evidenced as a feasible strategy for enhancing the photostability and photoluminescence of PbI2, facilitating the development of practical applications.

Structural and Photophysical Properties of Guanidinium–Iodide‐Treated Perovskite Solar Cells

“…For example, Li et al reported the PL emission from PbI 2 ; however, this was generated by a power density above 200 W cm −2 from a 405 nm laser, which is over 2000 times stronger than the power we used to excite PL from the perovskites here. [ 53 ] Therefore, in the PL images, PbI 2 presents as dark spots due to the extremely low emission signals. A second possibility is that the GAI affects in some way the noncubic phase observed in the SAED patterns (Figure 2e,f).…”