The Complex Interplay of Lead Halide Perovskites with Their Surroundings

Photoexcitation of lead halide perovskites induces a restructuration of the material that simultaneously enhances its emission properties and triggers its degradation. These concomitant processes are strongly dependent on the surroundings of the perovskite, both while and after being processed, underlining the relevance the environment and the interfacial design have in the stability and performance of these materials and the devices based on them. This shocking observation reveals that when subjected to external illumination, lead halide perovskites undergo a number of photophysical processes that strongly modify their structure and thus their optoelectronic properties. Such photoinduced instability stems from a defective structure directly linked to the low-temperature and solution-processed fabrication routes generally employed to build perovskite solar cells with efficiencies comparable to state-of-the-art values. On the other hand, these same inexpensive and unsophisticated procedures make this material a promising component in energy conversion devices. Here, an analysis is provided regarding the different impact on the perovskite structure, hence on its optoelectronic performance, that the interaction with its surroundings has, providing specific examples that highlight this interplay, describing the kind of modification it induces, and listing the related effects on the optoelectronic properties that should be accounted for when characterizing them.