Hybrid and lead-free metal halide perovskites are emerging as versatile semiconductors for next-generation optoelectronic technologies, spanning photodetection, energy harvesting, and neuromorphic electronics. However, their device performance is strongly governed by defect-mediated charge transport and by the availability of scalable and environmentally sustainable fabrication routes. In this talk, I will present recent advances from our group addressing both challenges through in-situ defect spectroscopy and wafer-scale fabrication strategies for hybrid and lead-free perovskite devices.

First, I will introduce threshold voltage transient spectroscopy (TVTS), a universal and non-invasive technique that enables the real-time characterisation of trap states in fully processed multifunctional 2D perovskite devices. Applied to single-crystal field-effect transistors based on 4-fluorophenethylammonium lead iodide (F-PEAI), which simultaneously operate as high-gain photodetectors, TVTS reveals the temperature-dependent evolution of trap states from deep majority-carrier trapping at cryogenic temperatures to shallow traps above 100 K. Strong retrapping processes enhance minority-carrier diffusion lengths and enable photodetector responsivities exceeding 120 A/W, highlighting the critical role of trap dynamics in governing optoelectronic performance [1]. These findings build upon our earlier demonstrations of highly sensitive sub-wavelength hybrid perovskite photodetectors and their defect-assisted transport mechanisms [2].

I will then discuss our efforts toward lead-free perovskite platforms, focusing on both defect-mediated transport and scalable fabrication. In particular, trap-assisted transport in the lead-free 2D perovskite PEA₂SnI₄ enables neuromorphic plasticity and synaptic functionalities, illustrating the opportunities offered by defect engineering in next-generation electronic systems  [3]. Complementarily, we demonstrate the first wafer-scale, room-temperature synthesis of antimony-based perovskite analogues (Cs₃Sb₂Br₉ and Cs₃Sb₂I₉) via radio-frequency magnetron sputtering—a solvent-free, industry-compatible technique widely used in semiconductor manufacturing. These films exhibit high crystallinity, tunable optical bandgaps, and excellent optoelectronic performance when integrated into photodetectors, achieving responsivities of 3.3 A/W, bandwidths up to 11 kHz, and detectivities of 1.7 × 10¹⁵ Jones [4].

Together, these results highlight how defect spectroscopy, trap engineering, and scalable fabrication can be combined to unlock high-performance and environmentally sustainable perovskite optoelectronics, paving the way toward multifunctional devices and large-area integrated photonic systems.