Waterproof and Flexible Perovskite Photodetector Enabled By P‐type Organic Molecular Rubrene with High Moisture and Mechanical Stability

Abstract Metal halide perovskite films have gained significant attention because of their remarkable optoelectronic performances. However, their poor stability upon the severe environment appears to be one of the main facets that impedes their further commercial applications. Herein, a method to improve the stability of flexible photodetectors under water and humidity environment without encapsulation is reported. The devices are fabricated using the physical vapor deposition method (Pulse Laser Deposition & Thermal Evaporation) under high‐vacuum conditions. An amorphous organic Rubrene film with low molecular polarity and high elastic modulus serves as both a protective layer and hole transport layer. After immersed in water for 6000 min, the photoluminescence intensity attenuation of films only decreased by a maximum of 10%. The demonstrator device, based on Rubrene/CsPbBr₃/ZnO heterojunction confirms that the strategy not only enhances device moisture and mechanical stability but also achieves high sensitivity in optoelectronic detection. In self‐powered mode, it has a fast response time of 79.4 µs /207.6 µs and a responsivity 124 mA W⁻¹. Additionally, the absence of encapsulation simplifies the fabrication of complex electrodes, making it suitable for various applications. This study highlights the potential use of amorphous organic films in improving the stability of perovskite‐based flexible devices.