High Open-circuit Voltage of Graphene-Based Photovoltaic Cells Modulated by Layer-by-Layer Transfer

TL;DR

This study demonstrates that the open-circuit voltage of graphene-based photovoltaic cells can be effectively modulated by controlling the number of graphene layers through a layer-by-layer transfer process, highlighting potential for flexible solar devices.

Contribution

It introduces a method to modulate photovoltaic response in graphene-semiconductor junctions by layer control, revealing the impact of graphene layers on work function and device performance.

Findings

Work functions of FLGs increase with more layers after annealing.

Photovoltaic behavior can be tuned by layer number despite random stacking.

Surface photovoltaic effects indicate electronic realignment in heterojunctions.

Abstract

Graphene has shown great application opportunities in future nanoelectronic devices due to its outstanding electronic properties. Moreover, its impressive optical properties have been attracting the interest of researchers, and, recently, the photovoltaic effects of a heterojunction structure embedded with few layer graphene (FLG) have been demonstrated. Here, we report the photovoltaic response of graphene-semiconductor junctions and the controlled open-circuit voltage (Voc) with varying numbers of graphene layers. After unavoidably adsorbed contaminants were removed from the FLGs, by means of in situ annealing, prepared by layer-by-layer transfer of the chemically grown graphene layer, the work functions of FLGs showed a sequential increase as the graphene layers increase, despite of random interlayer-stacking, resulting in the modulation of photovoltaic behaviors of FLGs/Si interfaces. The surface photovoltaic effects observed here show an electronic realignment in the depth direction in the FLG heterojunction systems, indicating future potential toward solar devices utilizing the excellent transparency and flexibility of FLG.