Accelerated Thermal Aging Effects on Carbon-Based Perovskite Solar Cells: A Joint Experimental and Theoretical Analysis

In the search for stable perovskite photovoltaic technology, carbon-based perovskite solar cells (C-PSCs) represent a valid, stable solution for near-future commercialization. However, a complete understanding of the operational device stability calls for assessing the device robustness under thermal stress. Herein, the device response is monitored upon a prolonged thermal cycle aging (heating the device for 1 month up to 80 °C) on state-of-the-art C-PSCs, often neglected, mimicking outdoor conditions. Device characterization is combined with in-house-developed advanced modeling of the current–voltage characteristics of the C-PSCs using an iterative fitting method based on the single-diode equation to extrapolate series (RS) and shunt (RSH) resistances. Two temperature regimes are identified: Below 50 °C C-PSCs are stable, and switching to 80 °C a slow device degradation takes place. This is associated with a net decrease of the device RSH, whereas the RS is unaltered, pointing to interface deterioration. Indeed, structural and optical analyses, by means of X-ray diffraction and photoluminescence studies, reveal no degradation of the perovskite bulk, providing clear evidence that perovskite/contact interfaces are the bottlenecks for thermal-induced degradation in C-PSCs.