To fully exploit the potential of perovskite technology for energy generation, it is crucial to perform comprehensive diagnostics of the dynamic evolution of the optical, structural, and electrical properties under varying temperatures, environmental conditions, illumination levels, electrical bias, over time.

A detailed understanding of perovskite behaviour begins at the material level, where the perovskite is examined independently from its integration into a device. Using in-situ spectroscopic ellipsometry, different kind of perovskite materials such as lead halide (e.g. CsPbI₃) [1,2,3] and lead-free perovskites (e.g. FASnI₃) [4,5] have been investigated over the time under precisely controlled light, temperature and environmental conditions. Tracking the evolution of their dielectric function enables the sensitive detection of the earliest signs of instability and phase transformation, signals that static measurements do not reveal. In-situ TEM and XRD further expand the description of the material’s behaviour by providing direct structural insight, allowing the optical signatures identified by ellipsometry to be cross-correlated with the corresponding crystallographic evolution. Together, these insights offer a clearer picture of the intrinsic stability of different perovskite compositions and their response to external stress, enabling more reliable predictions of material durability under operating conditions.

A broader understanding emerges when these materials are examined within complete, working devices. Once incorporated into an operating architecture, perovskites interact with interfaces, electric fields, and illumination in ways that fundamentally reshape their behavior. Here, in-operando characterization represents a natural and necessary evolution from in-situ methods. Through the combined use of X-ray diffraction, photoluminescence tracking, and real-time electrical measurements, the structural, optical, and photovoltaic evolution of mixed-halide perovskite absorbers have been monitored in real time under operational conditions [6]. Bandgap shift, ions redistribution, and lattice responses emerge simultaneously with changes in device performance. This dynamic, multi-channel view reveals mechanisms that remain hidden when materials are characterized independently from device operation, allowing to separate reversible behaviors from the earliest signatures of irreversible degradation, and to understand how composition or interface engineering can drive devices toward more resilient working operation. In addition, it allows to disentangle mutually correlated effects of light, bias and temperature on perovskite materials.  

Linking structural, optical, and electrical evolution across scales reveals how these materials truly operate in real conditions and provides the basis for predicting and controlling degradation mechanisms. This dynamic perspective is essential for advancing perovskite materials and architectures toward reliable, long-term deployment in next-generation optoelectronic technologies.