Improving Power Conversion Efficiency of Polycrystalline Si Solar Cells via Temperature Regulation

Abstract

Enhancing the power conversion efficiency (PCE) of solar cells remains a key focus in advancing photovoltaic technologies, particularly for applications in space and planetary exploration. Recently, it has been demonstrated that by inhibiting the thermal losses of monocrystalline single-junction Si solar cells, the PCE can be significantly improved. However, it remains unclear whether this strategy can be applied to other types of solar cells, e.g., polycrystalline Si solar cells. Here, we report a comparison of the impact of temperature on the PCE of polycrystalline single-junction Si solar cells using high-photon-energy (520 nm) and low-photon-energy (980 nm) lasers. A significant PCE increase from 9.3% (300 K) to 44.8% (40 K) was observed for the 520 nm laser, while for the 980 nm laser, the PCE increase is not significant. The difference is attributed to the suppression of thermal loss, which is more pronounced for high-energy photons. Furthermore, the grain boundary barrier in polysilicon causes scattering of carriers when using the 980 nm laser, but the scattering under the 520 nm laser can be neglected. Understanding these new observations opens opportunities for designing solar cells with even higher PCEs to provide efficient and powerful energy sources for cryogenic devices.