Abstract
Graphene/silicon (Gr/Si) Schottky barrier solar cells (SBSCs) are attractive for harvesting solar energy and have been gaining grounds for its low-cost solution-processing. The interfacial barrier between graphene and silicon facilitates the reducing excessive carrier recombination while accelerating the separation processes of photo-generated carriers at the interface, which empowers the performance of Gr/Si SBSCs. However, the difficulty to control the interface thickness prevents its application. Here, we introduce the graphene oxide quantum dots (GOQDs) as a unique interfacial modulation species with tunable thickness by controlling the GOQDs particle size. The power conversion efficiency (PCE) of 13.67% for Gr/Si-based SBSC with outstanding stability in the air is obtained with the optimal barrier thickness (26 nm) and particle size (4.15 nm) of GOQDs. The GOQDs in Gr/Si-based SBSCs provide the extra band bending which further enhances the PCE for its photovoltaic applications.
Highlights
The global energy transformation has been driven by alarming climate change and global economic growth needs, which demands a greater need for renewable energy and energy efficiency [1]
graphene oxide quantum dots (GOQDs) inherit the unique properties from both graphene and quantum dots and are generally regarded as special graphene with a single- or few-layer and size of several nanometers [37]. These hydrophilic groups at the edge and on the surface of GOQDs sheets facilitate the alignment, the dispersion, and the stability of sheets in aqueous solution during the filtration and cleaning process. This is beneficial to enhance the physical contact of the graphene-GOQDs-silicon interface
The unique quantum effect of GOQDs is a novel nanomaterial that can modify the interface in Gr/Si SBSCs and serve as a distinctive barrier at the interface
Summary
The global energy transformation has been driven by alarming climate change and global economic growth needs, which demands a greater need for renewable energy and energy efficiency [1]. Transferring graphene, which has a superior optical transmittance as well as electrical conductivity, onto a silicon substrate will make a simple Schottky junction solar cell [3, 4]. Enormous interests are drawn to study this graphene/silicon heterojunction solar cell because this 2D graphene has higher carrier mobility, more excellent thermal stability, and the broader optical absorption [5, 6]. The key to improving the PCE performance of Gr/Si SBSCs lies in the carrier’s ability to have efficient directional movement and the separation of carriers, which are influenced by the work function.
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