Qian Huang

High efficiency and high open-circuit voltage quadruple-junction silicon thin film solar cells for future electronic applications

Conversion of clean and renewable solar energy into electricity with photovoltaic (PV) devices, based on earth-abundant silicon elements to meet increasing global energy demands and environmental sustainability, has motivated various potential industrial and domestic applications. In addition to large-scale electricity production of market-dominant crystalline silicon PVs, the unique properties of silicon-based thin-film solar-cells (TFSCs) make them very attractive as affordable clean and safe energy devices. Herein, with large-scale and mature plasma-enhanced chemical vapor deposition (PECVD) process that can efficiently fabricate high-performing a-SiC:H, a-SiGe:H, a-Si:H, and μc-Si:H single- and various multi-junction TFSCs, we report a highly-efficient and flexibly tunable monolithic quadruple-junction silicon TFSC with a high photovoltage above 3.0 V and power conversion efficiency of 15.03% (NREL measured 14.58%). Our proposed high-voltage silicon TFSCs, with excellent performance, can further enrich the toolbox for functional photoelectrical devices and inspire possible future applications as highly promising power supply sources in charging electronics, splitting and disinfecting water, powering household electronic devices, solar to CO2 reduction, and other possible applications.

Origin of Photovoltage Enhancement via Interfacial Modification with Silver Nanoparticles Embedded in an a-SiC:H p-Type Layer in a-Si:H Solar Cells

We used silver nanoparticles (Ag-NPs) embedded in the p-type semiconductor layer of hydrogenated amorphous silicon (a-Si:H) solar cells in the Schottky barrier contact design to modify the interface between aluminum-doped ZnO (ZnO:Al, AZO) and p-type hydrogenated amorphous silicon carbide (p-a-SiC:H) without plasmonic absorption. The high work function of the Ag-NPs provided a good channel for the transport of photogenerated holes. A p-type nanocrystalline SiC:H layer was used to compensate for the real surface defects and voids on the surface of Ag-NPs to reduce recombination at the AZO/p-type layer interface, which then enhanced the photovoltage of single-junction a-Si:H solar cells to values as high as 1.01 V. The Ag-NPs were around 10 nm in diameter and thermally stable in the p-type a-SiC:H film at the solar-cell process temperature. We will also show that a wide range of photovoltages between 1.01 and 2.89 V could be obtained with single-, double-, and triple-junction solar cells based on the single-junction a-Si:H solar cells with tunable high photovoltage. These solar cells are suitable photocathodes for solar water-splitting applications.