Dynamic Control of Band Alignment and Built-In Potential in High Performance Self-Powered InSe/SnS₂ Van der Waals Photodetectors via Gas Molecular Physisorption

TY - JOUR

T1 - Dynamic Control of Band Alignment and Built-In Potential in High Performance Self-Powered InSe/SnS2 Van der Waals Photodetectors via Gas Molecular Physisorption

AU - Cao, Ze

AU - Abid, Mohamed

AU - Ó Coileáin, Cormac

AU - An, Fengjiang

AU - Chang, Ching Ray

AU - Wu, Yuh Renn

AU - Wu, Han Chun

N1 - Publisher Copyright: © 2026 The Author(s). Small Science published by Wiley-VCH GmbH.

PY - 2026/3

Y1 - 2026/3

N2 - Molecular physisorption provides a versatile strategy to dynamically tailor the optoelectronic properties of van der Waals (vdW) heterostructures, enabling extended carrier lifetimes, broadened spectral response, and erasable memory effects in self-powered photodetectors. Here, we report how NO2 physisorption precisely modulates band alignment and built-in potentials in self-powered InSe/SnS2 heterojunction photodetectors. Using electrostatic gating, we identify three distinct regimes: (I) a robust p–n configuration (Vg ≤ –50 V), where adsorption induces a collective electron-withdrawing effect, enabling efficient p-i-n-like behavior with near-ideal charge separation; (II) an intermediate p–n regime (–50 V < Vg < –30 V), where competing electron withdrawal and recombination effects allow dynamic tuning the electronic structure and optoelectronic properties, and (III) an illumination-sensitive n–n+ mode (Vg ≥ –30 V), where NO2 molecules act as recombination centers, suppressing the built-in potential. This dual control via gating and molecular adsorption provides unprecedented manipulation of charge separation and transport, opening avenues for next-generation multifunctional optoelectronic devices.

AB - Molecular physisorption provides a versatile strategy to dynamically tailor the optoelectronic properties of van der Waals (vdW) heterostructures, enabling extended carrier lifetimes, broadened spectral response, and erasable memory effects in self-powered photodetectors. Here, we report how NO2 physisorption precisely modulates band alignment and built-in potentials in self-powered InSe/SnS2 heterojunction photodetectors. Using electrostatic gating, we identify three distinct regimes: (I) a robust p–n configuration (Vg ≤ –50 V), where adsorption induces a collective electron-withdrawing effect, enabling efficient p-i-n-like behavior with near-ideal charge separation; (II) an intermediate p–n regime (–50 V < Vg < –30 V), where competing electron withdrawal and recombination effects allow dynamic tuning the electronic structure and optoelectronic properties, and (III) an illumination-sensitive n–n+ mode (Vg ≥ –30 V), where NO2 molecules act as recombination centers, suppressing the built-in potential. This dual control via gating and molecular adsorption provides unprecedented manipulation of charge separation and transport, opening avenues for next-generation multifunctional optoelectronic devices.

KW - InSe/SnS

KW - band alignment

KW - built-in potential

KW - gas physisorption

KW - self-powered photodetectors

KW - van der waals heterojunction

UR - https://www.scopus.com/pages/publications/105031955814

U2 - 10.1002/smsc.202500616

DO - 10.1002/smsc.202500616

M3 - Article

AN - SCOPUS:105031955814

SN - 2688-4046

VL - 6

JO - Small Science

JF - Small Science

IS - 3

M1 - e202500616

ER -