Research and developments in thin-film silicon photovoltaics

Abstract

The increasing demand for photovoltaic devices and the associated crystalline silicon feedstock demand scenario have led in the past years to the fast growth of the thin film silicon industry. The high potential for cost reduction and the suitability for building integration have initiated both industrial and research laboratories dynamisms for amorphous silicon and micro-crystalline silicon based photovoltaic technologies. The recent progress towards higher efficiencies thin film silicon solar cells obtained at the IMT-EPFL in Neuchatel in small-area laboratory and semi-large-area industrial Plasma Enhanced Chemical Vapor Deposition (PE-CVD) systems are reviewed. Advanced light trapping schemes are fundamental to reach high conversion efficiency and the potential of advanced Transparent Conductive Oxides (TCO) is presented, together with issues associated to the impact of the substrate morphology onto the growth of the silicon films. The recent improvements realized in amorphous-microcrystalline tandem solar cells on glass substrate are then presented, and the latest results on 1 cm 2 cells are reported with up to 13.3 % initial efficiency for small-area reactors and up to 12.3 % initial for large-area industrial reactors. Finally, the different strategies to reach an improved light confinement in a thin film solar cell deposited on a flexible substrate are discussed, with the incorporation of asymmetric intermediate reflectors. Results of micromorph solar cells in the n-i-p configuration with up to 9.8 % stabilized efficiency are reported.

Universality of non-Ohmic shunt leakage in thin-film solar cells

“…[1][2][3] Consequently, a wide variety of these technologies, including amorphous and microcrystalline silicon ͑a-Si: H / c-Si: H͒, 4 cadmium telluride ͑CdTe͒, copper indium gallium diselenide ͑CIGS͒, 5 and organic photovoltaics ͑OPVs͒, 6 are being developed and commercialized. These developments have necessitated a better understanding of thin film solar cell device physics, including important module performance variability issues.…”

A Systematic Evaluation Model for Solar Cell Technologies

“…In opposite, thin film solar cells require only a few microns of thickness of silicon on substrate compared to hundreds of microns of thickness for a wafer-based cell [8]. Nevertheless, there are some aspects that need to be improved for the thin film solar cells technology such as better solar radiation conversion efficiency, more product stability for different absorption rates of lights with different wavelengths, and lower deterioration capability after extensive sun exposure for longer product lifetime [13]. There is also a third-generation solar cell technology, which attempts to improve the conversion efficiencies light radiation of thin film technologies to 30-60% while maintaining low production costs [8].…”

“…Advanced production technologies can help reduce production cost, improve product quality, and increase yield rate, and these technologies can be related to process engineering, system integration, production automation, and process equipment [13]. Furthermore, the introduction of new materials (such as nano-and microcrystalline silicon thin film solar cell), advanced devices (such as laser scriber), and new methods (such as extremely thin absorber) can also enhance solar conversion efficiency, decrease production costs, and extend product lifetime [3,14].…”

“…Furthermore, the introduction of new materials (such as nano-and microcrystalline silicon thin film solar cell), advanced devices (such as laser scriber), and new methods (such as extremely thin absorber) can also enhance solar conversion efficiency, decrease production costs, and extend product lifetime [3,14]. The demand of raw materials increases substantially [13]. For example, glass substrate and silane, the material for making crystalline silicon, are essential materials for making thin film solar cells and modules [14].…”