Photovoltaic performance enhancement in monocrystalline silicon solar cells

Abstract

The approaching depletion of fossil fuels and the increasingly serious global climate change have driven people to search for clean and renewable alternative energy sources. Photovoltaic (PV) cells, which allow the transformation of sunlight directly into electric energy, are expected to play an important role in addressing the above-mentioned challenges. Despite of this huge potentiality, these devices are suffering from the low efficiency and high generation cost of electricity. To meet the ever-growing demand for energy in a sustainable manner, the production of cost-effective device has become the urgent affairs for the development of solar industry. In this work, applications of effective titanium dioxide (TiO2)-based aerogels nanomaterials and rare earth cations-activated photoluminescent down-conversion phosphor materials to the domain of energy conversion, particularly for the photovoltaic performance enhancement of single-junction monocrystalline silicon (mono-Si) solar cells are investigated. Improved conversion efficiency in solar cell was demonstrated by developing novel and low-cost anti-reflection coatings (ARCs) on the cell’s textured surface through screen printing technique. TiO2 has been widely used in silicon PV devices as ARCs owing to its outstanding optical properties. This study looks at investigating the influence of high surface area anatase TiO2 based nanoaerogels for the light harvesting enhancement in solar cells, specifically at the ultraviolet (UV)-blue wavelengths of solar spectrum. Mesoporous TiO2 and magnesium oxide (MgO)-doped TiO2 aerogels were prepared using a precipitation method in conjunction with a modified sol-gel process. The anti-reflection coating (ARC) was formed by screen printing an optimised mixture solution comprising TiO2-based aerogels nanomaterials and a co-polymer resin of ethylene vinyl acetate (EVA) on the textured surface solar cell. The obtained results revealed an optimum relative enhancement of 6.0% in conversion efficiency for MgO-doped TiO2 coating and 3.4% for the undoped-TiO2 under a simulated one-sun illumination. Given that the silicon solar cells exhibit weak response to the short wavelength of incident light, an alternative ingenious approach to suppress the spectral mismatch and increase the device efficiency has been executed based on the method of spectrum modification by employing down-converting photoluminescent phosphor materials. Silicon PV cells were coated with a luminescent layer composed of EVA and high-quantum yield terbium-activated gadolinium oxysulfide (Gd2O2S:Tb3+) phosphor using rotary screen printing. The modified cells showed an optimum enhancement of 3.6% in conversion efficiency relative to those for a bare cell. The obtained results also demonstrated that the down-conversion (DC) effect induced by the doping agent (Tb3+) is solely responsible for the PV cells performance enhancement.