Translucent and Color-Neutral Si Solar Cells Enabled by Laser-Drilled Microfunnel Arrays

We report a process-structure-performance analysis of Si microfunnel array solar cells for color-neutral translucent photovoltaic applications. Our rapid, maskless fabrication approach combines nanosecond UV microdrilling with selective wet etching enabled by a controlled SiO2 cap layer on Si. We show the etching-induced transformation of microholes into microfunnels in an HF-HNO3–CH3COOH (HNA) solution and analyze their junction quality and photovoltaic metrics as a function of etching duration. The resulting devices show color-neutral light transmission with enhanced optical scattering within the Si absorber, while retaining excellent diode behavior. Relative to planar controls, the microfunnel solar cells exhibit approximately 5% lower reflectance and about 3% color-neutral light transmission. The solar cells also exhibit a color rendering index (CRI) value above 95, indicating near-perfect color rendering comparable to natural daylight. Despite an ≈9% reduction in Si absorber volume, the devices retain over 95% of the planar open-circuit voltage (Voc) and fill factor (FF), while the short-circuit current density (Jsc) reaches nearly 90% of the planar controls. With further optimization of microfunnel geometry and surface passivation, this architecture may provide a viable platform for color-neutral, translucent Si solar cells for building-integrated photovoltaic applications.