Investigation of Degradation Mechanisms in Carbon-Based Perovskite Solar Cells Exposed to Damp-Heat Conditions

The efficiency of perovskite solar cells is continuously increasing in the last decade, reaching up to 25.5%. However, further investigation is required to improve the stability of such devices, starting with the identification of the degradation mechanisms upon exposure to harsh environments. For an increased durability of the devices at high levels of moisture and temperature, a mesoporous structure was adopted, utilising carbon electrode and omitting the hole transport layer, which is susceptible to heat. Furthermore, an adequate encapsulation is required for additional protection against moisture ingress. This scientific work aims at identifying the degradation paths followed by perovskite cells when they are subjected to high temperature and humidity levels. To achieve this goal, full carbon-based perovskite (c-PSC) cells and modified devices were encapsulated with various concepts, and aged either at damp-heat conditions (85% RH / 85°C) or at high temperature (85°C) in nitrogen environment. Moreover, different characterisation techniques were compared for the identification of the degradation mechanisms. The results indicate that perovskite reacts with moisture after 1000 hours of damp-heat exposure, while heat degradation occurs much earlier. The latter is detrimental and requires further improvement of the durability of the perovskite absorber to heat.