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.

Near Zero-Threshold Voltage P-N Junction Diodes Based on Super-Semiconducting Nanostructured Ag/Al Arrays.

Semiconductor devices are currently one of the most common energy consumption devices. Significantly reducing the energy consumption of semiconductor devices with advanced energy-efficient technologies is highly desirable. The discovery of super-semiconductors (SSCs) based on metallic bi-layer shell arrays provides an opportunity to realize ultra-low-power consumption semiconductor devices. As an example, the achievement of near zero-threshold voltage in p-n junction diodes based on super-semiconducting nanostructured Ag/Al arrays is reported, realizing ultra-low-power p-n junction diodes: ≈3 W per trillion diodes with a working voltage of 1 V or 30 mW per trillion diodes with an operating voltage of 0.1 V. In addition, the p-n junction diodes exhibit a high breakdown field of ≈1.1 × 106  V cm-1 , similar to that of SiC and GaN, due to a robust built-in field driven by infrared light photons. The SSC p-n diodes with near zero-threshold voltage and high breakdown field allow access to ultra-low-power semiconducting transistors, integrated circuits, chips, etc.