Towards linking lab and field lifetimes of perovskite solar cells

Metal halide perovskite solar cells (PSCs) represent a promising low-cost thin-film photovoltaic technology, with unprecedented power conversion efficiencies obtained for both single-junction and tandem applications1-8. To push PSCs towards commercialization, it is critical, albeit challenging, to understand device reliability under real-world outdoor conditions where multiple stress factors (for example, light, heat and humidity) coexist, generating complicated degradation behaviours9-13. To quickly guide PSC development, it is necessary to identify accelerated indoor testing protocols that can correlate specific stressors with observed degradation modes in fielded devices. Here we use a state-of-the-art positive-intrinsic-negative (p-i-n) PSC stack (with power conversion efficiencies of up to approximately 25.5%) to show that indoor accelerated stability tests can predict our six-month outdoor ageing tests. Device degradation rates under illumination and at elevated temperatures are most instructive for understanding outdoor device reliability. We also find that the indium tin oxide/self-assembled monolayer-based hole transport layer/perovskite interface most strongly affects our device operation stability. Improving the ion-blocking properties of the self-assembled monolayer hole transport layer increases averaged device operational stability at 50 degrees C-85 degrees C by a factor of about 2.8, reaching over 1,000 h at 85 degrees C and to near 8,200 h at 50 degrees C, with a projected 20% degradation, which is among the best to date for high-efficiency p-i-n PSCs14-17. We correlate lab test and field test results to better predict the performance of perovskite photovoltaics as a step towards real-world implementation.