Performance of multi-junction silicon-based thin film solar cells under concentrated sunlight

Abstract

Multi-junction silicon-based thin-film concentrator solar cells are promising candidate to achieve both low-cost and high-efficiency. For the application of silicon-based thin film solar cells to concentrator photovoltaics, it is required to be revealed the light intensity dependence of the performance of silicon-based thin film solar cells. From these reasons, in this study both calculation and experimental studies were conducted with several types of single-junction and multi-junction tandem solar cells. From both simulation and measurement results, we observed that double-and triple-junction solar cells achieve high open-circuit voltage and large logarithmic increment in open-circuit voltage with increasing lightintensities. On the other hand, it became clear that the drop of fill factor is required to be improved for the realization of the multi-junction silicon-based thin-film solar cells with very high efficiency under low concentration ratios of sunlight.

A review of concentrator silicon solar cells

“…Kasashima et al used a heterojunction microcrystalline silicon (μc-Si:H) thin film cell which was made by plasma enhanced chemical vapor deposition (PECVD) for concentration, they deposited wide bandgap microcrystalline silicon oxide (μc-Si 1 À x O x :H) film as the top P-type layer to decrease the recombination of carriers, the efficiency of the cell reached 10.4% under 11.8 suns [98]. They also used two-junction and three-junction cells made of a-Si:H and μc-Si:H films for concentration, the current mismatch between the sub-cells increased with concentration ratio, the two-junction cell had the highest efficiency of 12.2% under 2.7 suns [99]. They also did numerical analysis to above cells using the AMPS-1D (Analysis of Microelectronic and Photonic Structures) software and found that the efficiencies of single-junction and three-junction cells could reach 13% and 23% under 50 suns after optimization [98,99].…”

“…They also used two-junction and three-junction cells made of a-Si:H and μc-Si:H films for concentration, the current mismatch between the sub-cells increased with concentration ratio, the two-junction cell had the highest efficiency of 12.2% under 2.7 suns [99]. They also did numerical analysis to above cells using the AMPS-1D (Analysis of Microelectronic and Photonic Structures) software and found that the efficiencies of single-junction and three-junction cells could reach 13% and 23% under 50 suns after optimization [98,99]. However, the light-induced recession of the thin film cells will be more serious under concentration, the fill factor and efficiency of the cell decreased quickly with the increase of illumination time under 10 suns [100].…”

“…The back contact cells have been used under 7 suns [74], the HIT cell with the highest efficiency of 25.6% also used back contact structure, and its efficiency will increase under a certain concentration ratio. The microcells and silicon based thin film cells have low costs, but their efficiencies are low (η o12.2%) and could only be used for low concentration [93,99]. The VMJ cell has the smallest series resistance among all cells, its costs is low, its highest efficiency is 19.48% under very high concentration (1200 suns) [24] and will increase after optimizing the manufacturing process and device parameters.…”

Performance of Integrated Thin-Film Silicon Solar Cell-Based Water-Splitting Devices under Varying Illumination Angles and an Estimation of Their Annual Hydrogen Production

“…In the case of a static device position, which results in a reduced illumination intensity, , the decrease of J SC can be related to the decreased amount of photons absorbed by the photovoltaic device. On the other hand, changes in V OC are directly related to the splitting of the quasi-Fermi level under illumination. , Here, we observed that a slight improvement in fill factor (FF) values upon changes in the angle between 0 and 60° has an analogous origin to the effects of the decreased photon flux on the solar cell performance. , These effects are usually related to the distribution of the field in the solar cell upon illumination and a lower recombination rate of electron–hole pairs in the active layer of the solar cell. , Note that here an improvement in the built-in field brings no positive effect on V OC , which is dictated by the reduced number of the photogenerated electron–hole pairs and consequently reduced quasi-Fermi level splitting with an increasing angle.…”

The Influence of Operation Temperature and Variations of the Illumination on the Performance of Integrated Photoelectrochemical Water‐Splitting Devices

“…For the FF , no clear trend is observed for the temperatures investigated. For temperatures below 40 °C, the fill factor decreases with increasing intensity; while for higher temperatures the fill factor increases with an increasing intensity, suggesting a tradeoff between several competing mechanisms (such as possible changes in recombination and/or field distribution profiles in the sub cells), influencing FF over temperature and intensity range. The resulting efficiency η shows an increase with increasing intensity, but a decrease with increasing temperature …”