Improving the efficiency of silicon solar cells using in situ fabricated perovskite quantum dots as luminescence downshifting materials

Luminescence downshifting (LDS) layer integration has been proven to be an efficient way to ameliorate the poor UV-blue spectral response and improve the power conversion efficiency (PCE) for solar cells (SCs). By employing an in situ fabricated CH3NH3PbBr3 (CH3NH3 = methylammonium, MAPbBr3) quantum dot/polyacrylonitrile (PAN) composite film as the LDS layer, we observed a clear enhancement in the external quantum efficiency (EQE) for silicon SCs, predominantly in the UV-blue region. With a theoretically calculated intrinsic LDS efficiency (ηLDS) of up to 72%, silicon SCs with the LDS layer exhibited an absolute value of 1% for PCE improvement in comparison to those without the LDS layer. The combination of easy fabrication and low cost makes it a practical way to achieve photovoltaic enhancement of Si-based SCs

Enhanced Performance of InGaN Light-Emitting Diodes via High-Quality GaN and Embedded Air Voids Grown on Hexagonal 3D Serpentine Mask Sapphire Substrates

This work demonstrates high-efficiency InGaN-based light-emitting diodes (HSM-LEDs) prepared on hexagonal 3D serpentine sapphire substrates. The 3D serpentine mask has a modulating effect on epitaxial lateral growth (ELOG), which can not only reduce the dislocation density (TDD) to 1.7 × 107 cm–2 without any high dislocation density (HDD) region but also induce the formation of a hexagonal pyramidal air-void array with an inclination angle of 65°. Compared to conventional LEDs, HSM-LEDs exhibit a 117% enhancement in EL output power at a current injection of 600 mA. This can be attributed to the improvement of crystal quality by modulated ELOG, the relief of in-plane stresses to mitigate the quantum-confined Stark effect (QCSE) through the weak connection of the epitaxial layer to the substrate, and the enhanced light extraction efficiency by an embedded air-void array. We confirmed the reduction of compressive stress from 0.94 GPa to 0.51 GPa in HSM-LEDs by Raman spectroscopy and investigated the effect of air voids on light extraction efficiency (LEE) experimentally and theoretically. Ray-tracing simulations show that the embedded pyramidal air voids can effectively re-extract the downward emitted light, and the pyramidal air voids with a 65° slant sidewall can improve the LEE by 71%