Carbon quantum dots interfacial modified graphene/silicon Schottky barrier solar cell

Abstract

The two-dimensional thin film, as an effective interface modification layer to improve the power conversion efficiency (PCE) of graphene/silicon (Gr/Si) heterojunction solar cells has attracted extensive attention recently. However, the complicated manufacturing process and specialized equipment requirements impede its broad application. Herein, carbon quantum dots (CQDs) fabricated under the mild reaction condition was first time used to modify Gr/Si devices interface structure. The effects of CQDs size distributions and coating thickness on J-V characteristics and the energy band structure of Gr/CQDs/Si solar cells were systematically analyzed. The results indicate that the PCE of resulting Gr/CQDs/Si solar cells could reach 9.97% when the thickness and sizes of CQDs interlayer are ∼26 nm and 4–7 nm, without any chemical doping, which is 6.8-times PCE than that of virgin Gr/Si solar cells. The CQDs interlayer serves as both an electron blocking layer and hole transport layer to reduce the carrier recombination, leading to a lower reverse saturation current as well as a larger V OC then improved the device performance. The enhanced PCE shows that the CQDs species have the potential applications in a cost-effective photovoltaic device. • Novel Gr/CQDs/Si solar cell is demonstrated through a simple solution process. • The cleaner graphene transfer method based on cyclododecane species was achieved. • The enhanced PCE of 9.97% was achieved for ∼26 nm thickness GQDs with interlayer size of 4–7 nm. • The energy band structure of Gr/CQDs/Si solar cells were systematically analyzed.