Gravity-driven gradient engineering of room-temperature perovskite thin films for spectral and photodetection applications

Integration and miniaturization of optoelectronic devices are pivotal for advancing their transition from specialized instruments to consumer electronics. Laterally graded thin films enable multiple device arrays to be realized on a single chip without stacking or assembling multiple discrete films, thereby reducing space occupation. Among them, gradient-thickness thin films replace chemical dimension control (composition) with physical dimension control (thickness), avoiding impurities or lattice mismatches associated with compositional variations. In this work, gradient-thickness perovskite thin films were realized by combining the rapid crystallization of room-temperature processed perovskites with gravity-driven deposition on inclined substrates, which provides a low-cost, room-temperature pathway to wide-range, high-resolution gradient-thickness perovskite thin films. Subsequently, p–i–n structured photodetector arrays were implemented into distinct thickness regions of a single film. The adopted configuration was utilized to construct a miniaturized spectrometer capable of detecting light in the visible wavelength range with a spectral error below 5 nm. Moreover, the proposed design emphasizes the ability to analyze the red, green, and blue components of multicolor light, highlighting its potential for composite light sensing and color imaging applications.