A ferroelectrically modulated ultrasensitive two-dimensional perovskite phototransistor with zero-gate-bias

Two-dimensional (2D) organic-inorganic halide perovskites are promising sensitive materials for optoelectronic applications due to their strong light-matter interactions, layered structure, long carrier lifetime and diffusion length. However, a high gate bias is indispensable for perovskite-based phototransistors to optimize detection performances, since ion migration seriously screens the gate electric field and the deposition process introduces intrinsic defects, which induces severe leakages and large power dissipation. In this work, an ultrasensitive phototransistor based on the (PEA)₂SnI₄ perovskite and the Al:HfO₂ ferroelectric layer is meticulously studied, working without an external gate voltage. The nonvolatile remanent polarization provides a stable floating gate to locally define the potential profile, regulate barrier contact, and modulate carrier transport properties and charge redistributions, which facilitates an ultralow level of dark current and accurate photocurrent extraction at zero gate bias. Consequently, the fabricated phototransistor exhibits an outstanding responsivity and detectivity of 4918 A W^-1 and 2.15 × 10¹⁵ Jones, respectively. The developed phototransistor contributes to advancements in optoelectronic applications including large-scale intelligent sensor arrays, light-wave communications and integrated circuits.