Advances in Solar Energy: Solar Cells and Their Applications

This chapter will focus on the recent advances on the traditional and modern solar cell technologies, notably, (a) silicon solar cells, (b) multi-junction solar cells, (c) perovskite solar cells, and (d) dye-sensitized solar cells. Research efforts focused on improvement of the stability and the efficiency of each type of cells will be mentioned. While the current industrial market is predominantly dominated by silicon solar cells, other photovoltaic cells (b–d) show immense promise to overtake the silicon PV market in near future. The most efficient silicon solar cell reported reaches an efficiency of over 26%. This efficiency was achieved by fabricating a cell with an interdigitated back contact, combining n-type and p-type amorphous silicon to collect both holes and electrons. The back contact is separated from the front contact by crystalline silicon, with the front contact covered by an amorphous silicon passivation layer and an antireflective coating. A close competitor of silicon solar cells, known as multi-junction solar cells, displays power conversion efficiency as high as 46% using a solar concentrator. However, due to difficulty in cell fabrication with elevated cost, application of this type of cell is mostly limited to extraterrestrial purposes. A low-cost alternative of multi-junction cell is a perovskite solar cell. The best efficient perovskite solar cell with a power conversion efficiency of 23.9% was achieved by using a complex semitransparent organic–inorganic perovskite material with a high bandgap absorber, Cs0.1(H2NCHNH2)0.9PbI2.865Br0.135 combined with a low bandgap absorber, c-Si, for the back contact. While the perovskite solar cells are promising candidates as low-cost substitute to silicon solar cells, stability remains an issue for the former. On the other hand, dye-sensitized solar cells are cost-effective and chemically stable, with a best reported efficiency of 13% using a panchromatic donor–π–acceptor-based designed SM315 as an organic sensitizer; power conversion efficiency of this type of cell is still to be improved to overtake the silicon PV market