Pyramid‐Shaped Perovskite Single‐Crystal Growth and Application for High‐Performance Photodetector

To boost the power conversion efficiency of silicon/perovskite tandem solar cells, pyramid‐textured structures have been investigated and introduced into devices. However, high‐quality pyramid‐shaped single crystal preparation is an obstacle in tandem device development. Perovskite crystals obtained using general methods are cubic because of their structural symmetry and rapid growth rate. In this study, based on mass transfer boundary layer theory, a pyramid‐shaped perovskite single crystal is successfully obtained using an asymmetrically spatial confinement‐induced crystallization method. The synthesized pyramid crystals exhibited high crystallinity and enhanced optical absorption. A photodetector constructed using the as‐grown crystal exhibited high‐performance properties, including a responsivity of 9.4 A W−1, photo‐to‐dark current ratio of 2.3 × 104, and detectivity of 2.1 × 1011 Jones. Its unique insensitivity to the incident photon direction is also characterized. The flexible photodetector also exhibited excellent responsivity under different bending curvature radii. Additionally, the light‐trapping effect and absorption superiority of pyramid crystals over cuboid crystals are well established based on a semi‐empirical analytical model. This breakthrough in pyramid‐shaped perovskite crystal preparation provides a promising approach for the development of novel tandem solar cells and other optoelectronic devices.