Moisture-tolerant and high-quality α-CsPbI3 films for efficient and stable perovskite solar modules

Abstract

All-inorganic perovskite solar cells (PSCs) are attracting considerable attention due to their excellent thermal stability. However, their unsatisfactory power-conversion efficiency and moisture instability lead to challenges for practical commercialization. Here, a facile but effective strategy is demonstrated to stabilize/passivate the cubic phase of CsPbI₃ by inhibiting the moisture invasion using 18-crown-6 ether (Crown). The strong interaction between Crown and surface Cs⁺ ion not only effectively improved the moisture tolerance, but also simultaneously reduced surface defects and related migrations, thus accordingly improving the phase and operation stability of the CsPbI₃ films and devices. Based on the obtained high-quality CsPbI₃–Crown films, PSCs with up to 16.9% efficiency were fabricated. The devices readily maintained ∼91% of the initial PCE for more than 1000 h (85 °C, N₂) and even ∼90% for up to 2000 h (relative humidity 20%) without encapsulation. More importantly, the developed strategy has been successfully used to fabricate large-area CsPbI₃ modules, showing an efficiency of up to 11.8% with the 16 cm² total area. A stability performance that can retain ∼95% of the original value for over 500 h (operating conditions, relative humidity 60%) with encapsulation has also been achieved in the first PSC module based on the CsPbI₃ system.