First demonstration of lead free CsSnI3 on GaN hybrid heterostructure for dual mode, broadband and self powering photo sensing

Photoelectronic and image sensors based on perovskite hybrid heterojunctions play a significant role in defense, navigation, security surveillance, and space applications. This article reports, for the first time, the fabrication of a CsSnI 3 /GaN hybrid photodetector architecture designed to exhibit superior broadband photon absorption across the ultraviolet-to-infrared regime, without the need for additional charge-transport, encapsulation, or interfacial layers. First-principles calculations based on Density Functional Theory were implemented to investigate the electronic properties of the CsSnI 3 /GaN heterostructure. X-ray diffraction and scanning electron microscopy reveal that the controlled addition of ascorbic acid and 2-methylaminopyridine promotes the growth of a highly crystalline CsSnI 3 layer with uniform morphology and larger grains on the GaN substrate. . Cross-sectional scanning electron microscopy and transmission electron microscopy reveal a compact, well-defined heterointerface that promotes efficient carrier transport. The absorption spectra show a range extended towards the infrared region. Photoluminescence spectra show quenched emission intensity, while time-resolved photoluminescence and electrochemical impedance spectroscopy measurements reveal a shorter carrier lifetime in the CsSnI 3 /GaN heterojunction, confirming suppressed recombination losses, more efficient separation of photogenerated carriers, and reduced carrier trapping at interfacial defects. Photoelectric measurements further prove dual-mode operation (self-powered and biased) with broad spectral photoresponsivity from the ultraviolet to the near-infrared. Under self-powered mode, the photosensitivity reaches 0.11 A/W at 2.5 mW/cm 2 , with a specific detectivity of 7.5 × 10 10 Jones, a noise-equivalent power of 4 × 10 − 12 W/√Hz, a linear dynamic range of 100.4 dB, and a rise/decay time ratio of 1.15/2.1 ms. Under − 2 V external bias, the responsivity is further enhanced to 4.3 A/W with a specific detectivity of 8 × 10 12 Jones, indicating a faster response time. These findings establish this hybrid heterostructure as a promising platform to integrate lead-free Sn-based perovskites on large-scale substrates for high-efficiency, sustainable, and stable hybrid photodetector applications.