Interface-dominated photocurrent suppression in ZnO/MAPbI₃/Ag phototransistors

초록

This work investigates zinc oxide (ZnO)-templated methylammonium lead iodide (MAPbI₃) field-effect transistors with and without silver (Ag) nanodots, focusing on how the ZnO/perovskite buried interface and Ag-induced surface doping jointly govern charge transport and photoresponse. Although Ag nanodots are generally introduced to enhance device performance through plasmonic effects, incorporating a ZnO templating layer leads to a fundamentally different operating behavior. From a structural perspective, the ZnO underlayer induces the formation of larger perovskite grains, which markedly enhances dark p-channel conductivity by suppressing carrier scattering. In contrast, under optical excitation, the Ag-decorated MAPbI₃/ZnO heterostructure exhibits pronounced photocurrent suppression, resulting in poorer photoresponse compared to the pristine device. This counterintuitive behavior is strongly supported by device-level evidence indicating nonradiative recombination and efficient carrier quenching at the electronically mismatched n-type ZnO/p-doped Ag–perovskite interface. Together, these findings highlight a critical trade-off between morphological benefits and interfacial recombination losses, defining important design limitations for hybrid perovskite optoelectronic devices. © 2026 Elsevier B.V.

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