Efficient Stabilization and Passivation for Low-Temperature-Processed γ-CsPbI3 Solar Cells

The inorganic CsPbI3 perovskite has attracted tremendous attention in the photovoltaic fields for its chemical stability and suitable band gap. Generally, CsPbI3 solar cells with decent performances adopted high annealing temperature to form high-quality black-phase perovskite films. The high-temperature process hinders its practical application and further development. Hence, fabricating stable black-phase CsPbI3 at low temperature is imperative and necessary. In this work, a new additive p-xylilenediamine bromide (PhDMADBr) is reported to facilitate the synthesis of solution-processed, high-quality, and stable gamma-CsPbI3 films at a surprisingly low temperature of 60 degrees C. The additive with an appropriate content can effectively improve both the film morphology and crystallinity of gamma-CsPbI3 perovskite films. PhDMADBr anchors to the perovskite surface or grain boundaries as a protection through hydrogen bonding between its ammonium cations and CsPbI3. In addition, the Br element introduced by the additive passivates I- vacancies in perovskite films, resulting in the improvement of both phase stability and devices' performance. Finally, the PSCs based on the modified gamma-CsPbI3 perovskite film achieve a champion efficiency of 12.71%. Moreover, the device retains 85% of its original efficiency after being kept for 1000 h.

Automated summary

A new additive, p-xylilenediamine bromide (PhDMADBr), is reported to facilitate the synthesis of high-quality and stable gamma-CsPbI3 films at a surprisingly low temperature of 60 degrees C. The additive improves film morphology and crystallinity, as well as phase stability and device performance. Photovoltaic cells based on the modified gamma-CsPbI3 film achieved a champion efficiency of 12.71% and retained 85% of its original efficiency after being kept for 1000 hours.