Combined power of perovskites and silicon solar cells: Comparison between vapor-deposited and solution-processed perovskite layers

摘要

The photovoltaic (PV) or solar cells technology can be categorised into two main groups, the wafer-based and thin-film based PVs. The wafer-based PVs include the commonly known crystalline silicon (c-Si) and gallium arsenide (GaAs) cells. The GaAs cells exhibit higher efficiency compared to crystalline silicon (c-Si) cells but it is the later that dominates the commercial market. Thin-film based (2nd Generation) PVs, including cadmium telluride (CdTe), amorphous silicon (a-Si:H) and copper-indium-gallium-selenide (CIGS), generally absorb light more efficiently than wafer-based cells and can allow the use of materials in very thin films form. CdTe PVs have proven to be highly efficient but holds only a few percentage share of the market. There is still a need for more R&D before further commercialisation. An emerging and relatively new class of thin-film based photovoltaics (3rd Generation) technology that has the potential to overcome the current energy conversion efficiencies and performance by making use of novel materials. This class of PVs include organic photovoltaic (OPV), dye-synthesised solar cells (DSSC), quantum-dot (QD) and last but not least, the perovskite PV. Perovskite PVs can offer a low cost energy generation solution with the best device conversion efficiencies have shot from lower than 4% in 2009 to more than 21% in 2016. Perovskite based devices can be fabricated using vacuum thermal evaporation or by solution processing of the active layers. Although most recent perovskite solar cells with record efficiencies (>20%) are prepared via solution processing, the early breakthrough in perovskite solar cells was made with vacuum processed perovskites thin films. Vacuum thermal evaporation offers the ability and flexibility to prepare solar cell devices in various configuration. Recent developments in the field of perovskite demonstrates its compatibility with both, first and second generation PV technologies, and is therefore likely to be embraced by the conventional PV industry and make its way into utility-scale power generation.