Transparent Beads Mitigate Incident-Angle Loss in Silicon Microwire Solar Cells

Efficient management of incident light─maximizing absorption while suppressing reflection─is essential for sustaining the power conversion efficiency (PCE) of solar cells under real operating conditions. However, since the position of the sun changes depending on the season and time of day, the light absorption in solar cells fluctuates, decreasing as the angle of incidence increases. To maximize solar power generation, it is therefore essential to mitigate angle-induced light absorption losses. In this study, we employed crystalline silicon microwire arrays to enhance light trapping and reduce incidence-angle-dependent losses. Additionally, transparent, light-scattering silica beads were inserted layer by layer using the Langmuir-Blodgett dip-coating technique, which enabled systematic control of bead thickness from a monolayer to sextuple layers. Among these, the double-layer configuration was found to be optimal, yielding the highest photocurrent density and efficiency. The PCE of planar solar cells decreased by over 38.1% when the incident angle increased from 0° to 50°, whereas the PCE of the solar cells with microwires and silica beads in between decreased by less than 11.9%. Notably, outdoor seasonal calculations revealed that the silica bead integrated structure achieved a cumulative power output of 36.09 MJ/m², corresponding to 27.5 and 7.4% improvements compared to planar and microwire cells, respectively, thereby validating its practical applicability. This work provides a simple and effective strategy to reduce the angular dependence of PCE degradation in solar cells.