Doubling Power Conversion Efficiency of Si Solar Cells.

Improving solar cells' power conversion efficiency (PCE) is crucial to further the deployment of renewable electricity. In addition, solar cells cannot function at exceedingly low temperatures owing to the carrier freeze-out phenomenon. This report demonstrates that through temperature regulation, the PCE of monocrystalline single-junction silicon solar cells can be doubled to 50-60% under monochromatic lasers and the full spectrum of AM 1.5 light at low temperatures of 30-50 K by inhibiting the lattice atoms' thermal oscillations for suppressing thermal loss, an inherent feature of monocrystalline Si cells. Moreover, the light penetration, determined by its wavelength, plays a critical role in alleviating the carrier freeze-out effect and broadening the operational temperature range of silicon cells to temperatures as low as 10 K. Understanding these new observations opens tremendous opportunities for designing solar cells with even higher PCE to provide efficient and powerful energy sources for cryogenic devices and outer and deep space explorations.