Intrinsic chemical stability of hybrid perovskites and their connection to the operational stability of perovskite solar cell devices
Lead halide based perovskites have emerged as promising active materials for photovoltaic cells. Enormous efforts have been devoted to device fabrication and optimization leading to power conversion efficiencies exceeding 25%, which gives perovskite solar cells the competitive advantage over many other well-known solar technologies. Despite superb efficiencies achieved in laboratory-scale devices, it was soon recognized that long-term stability was rapidly compromised under ambient conditions and such instability could jeopardize the future of perovskite solar cells.
In the present communication, a clear demarcation line between photo- and thermal degradation processes is traced. Based on experimental evidence, a clear distinction between true decomposition reactions and evaporation-like processes suffered by the organic cation is done. The halide effect on stability is discussed in terms of energy barriers during degradation reactions and clear distinction between inner or intrinsic stability of the active material and operational stability of devices (solar cells) is done outlining current strategies to overcome the long-term instability problems.