Hybrid organic-inorganic perovskite solar cells have recently emerged as a highly promising and inexpensive solution for sustainable energy. However, a full comprehensive picture of the phase transition including structural evolution and crystal growth mechanisms is missing for both scalable printing and lab-based spin-coating processes. Here we reveal fundamental insights into the perovskite phase transition when moving between spin-coating and printing processes, providing a rational path toward optimization of printed devices.

We report a Ruddlesden–Popper/3D heterostructure combined with molecule passivation within α-phase FAPbI3 films for high-performance and ambient-air-stable solar cells.

Perovskite solar cells based on two-dimensional/three-dimensional (2D/3D) hierarchical structure have attracted significant attention in recent years due to their promising photovoltaic performance and stability. However, obtaining a detailed understanding of interfacial mechanism at the 2D/3D heterojunction, for example, the ligand-chemistrydependent nature of the 2D/3D heterojunction and its influence on charge collection and the final photovoltaic outcome, is not yet fully developed. Here we demonstrate the underlying 3D phase templates growth of quantum wells (QWs) within a 2D capping layer, which is further influenced by the fluorination of spacers and compositional engineering in terms of thickness distribution and orientation. Better QW alignment and faster dynamics of charge transfer at the 2D/3D heterojunction result in higher charge mobility and lower charge recombination loss, largely explaining the significant improvements in charge collection and open-circuit voltage (V OC ) in complete solar cells. As a result, 2D/3D solar cells with a power-conversion efficiency of 21.15% were achieved, significantly higher than the 3D counterpart (19.02%). This work provides key missing information on how interfacial engineering influences the desirable electronic properties of the 2D/3D hierarchical films and device performance via ligand chemistry and compositional engineering in the QW layer.

All‐inorganic CsPbI3 holds promise for efficient tandem solar cells, but reported fabrication techniques are not transferrable to scalable manufacturing methods. Herein, printable CsPbI3 solar cells are reported, in which the charge transporting layers and photoactive layer are deposited by fast blade‐coating at a low temperature (≤100 °C) in ambient conditions. High‐quality CsPbI3 films are grown via introducing a low concentration of the multifunctional molecular additive Zn(C6F5)2, which reconciles the conflict between air‐flow‐assisted fast drying and low‐quality film including energy misalignment and trap formation. Material analysis reveals a preferential accumulation of the additive close to the perovskite/SnO2 interface and strong chemisorption on the perovskite surface, which leads to the formation of energy gradients and suppressed trap formation within the perovskite film, as well as a 150 meV improvement of the energetic alignment at the perovskite/SnO2 interface. The combined benefits translate into significant enhancement of the power conversion efficiency to 19% for printable solar cells. The devices without encapsulation degrade only by ≈2% after 700 h in air conditions.

All-inorganic halide perovskites hold promise for emerging thin-film photovoltaics due to their excellent thermal stability. Unfortunately, it has been challenging to achieve high-quality thin films over large areas using scalable methods under realistic ambient conditions. Here, we provide important lessons on controlling the solidification and crystallization of CsPbI2Br perovskite inks during ambient scalable fabrication, with results of superior thin-film quality and device performance compared to lab-scale processes.