Energy-Dependent Z-Scheme via Metal-Interfacing Two-Dimensional p-Type and n-Type Semiconductor Layers for Efficient Optoelectronic Conversion

Abstract

Hybrid heterostructures are a promising type of materials framework for optoelectronic conversion. We designed a ternary energy-dependent thin layer of Cu2S–Pt–WO3 (p-type–metal–n-type) heterojunction to explore an alternative way of realizing efficient charge separation. First-principles calculations showed that the Fermi level of the whole system is lined up via the mediation of Pt metal, which fosters the combination of holes in Cu2S and electrons in WO3 and keeps electrons in Cu2S and holes in WO3 well separated. Importantly, creation of band bending and charge polarization steer low-energy charges selectively to the intermediate metal and keep high-energy charges on individual semiconductors apart. Our simulation analysis of two-dimensional layers with the metal bridge shows increased charge flows across the junction compared to that of their bulk counterparts. Overall, this heterojunction is viable for suppressing recombination of photogenerated electron–hole pairs and augmented electrons per surface that would allow enhanced optoelectronic conversion.

Enabling Efficient Charge Separation for Optoelectronic Conversion via an Energy-Dependent Z-Scheme n-Semiconductor–Metal–p-Semiconductor Schottky Heterojunction

“…To overcome this challenge, we propose an energy-dependent S n –m–S p heterostructure model (Figure ) that integrates the merits of the Z -scheme, p–n, and s–m. Compared to our previous design of the S p –m–S n system based on two s–m Ohmic heterojunctions, this S n –m–S p design is more feasible since most noble metals possess higher (lower) work functions than n-type (p-type) semiconductors which favor the formation of the Schottky barrier. Moreover, the advantages of Schottky-based S n –m–S p heterojunction design include the following: (1) Formation of an inner electric field assisted by band-bending that performs two important functions.…”

Charge Steering in Heterojunction Photocatalysis: General Principles, Design, Construction, and Challenges

“…This system demonstrates increased charge flow across the junction compared to its bulk counterpart and exhibits a higher electron density on each surface that should produce enhanced optoelectronic conversion. [58] 6. Semiconductor-Graphene Heterojunctions Until now, achieving good charge separation and absorption of broad-spectrum visible light either in a single semiconductor or by the interfacing of two semiconductors either alone or with metal is a challenge that has prevented their practical application.…”

“…This system demonstrates increased charge flow across the junction compared to its bulk counterpart and exhibits a higher electron density on each surface that should produce enhanced optoelectronic conversion. [ 58 ]…”