Researchers at St. Mary's School-Wuhan and Guizhou Institute of Technology have demonstrated a simple light-management strategy for perovskite solar cells (PSCs) by introducing a Zn2SiO4 rear light-reflecting layer fabricated via a doctor-blade coating process. The approach targets optical losses in the visible spectrum and enhances device performance without modifying the core device architecture.
The Zn2SiO4 layer exhibits strong reflectivity across the 450-780 nm wavelength range, effectively reflecting transmitted photons back into the perovskite absorber. This recycled light increases the probability of photon absorption within the active layer, leading to measurable improvements in device output. External quantum efficiency (EQE) is enhanced across this spectral region, directly translating into an increase in the EQE-integrated short-circuit current density (Jsc) from 16.00 to 16.40 mA cm−2.
As a result of the improved light harvesting, the power conversion efficiency (PCE) rises from 17.71% to 18.06%. While the absolute gain is modest, it is achieved through a low-cost and scalable process, highlighting the practicality of the method.
Importantly, the study also reports a change in the Jsc-light intensity relationship. The slope increases from 1.10 to 1.75, indicating reduced recombination losses and more efficient charge collection. This suggests that the reflected photons are not only reabsorbed but also effectively contribute to carrier generation and extraction.
Compared to other light-management approaches, such as metallic reflectors, distributed Bragg reflectors (DBRs), or nanostructured photonic systems - the Zn2SiO4 layer offers a significantly simpler alternative. Conventional metal reflectors can introduce parasitic absorption and increase costs, while DBRs and nanostructures often require complex fabrication processes. In contrast, Zn2SiO4 provides high visible-near-infrared reflectance and can be deposited easily without intricate processing steps.
Overall, this work demonstrates that a straightforward rear-side modification can improve PSC performance by enhancing light utilization within a defined wavelength range. Although it does not aim for record efficiencies, the method presents a practical and cost-effective pathway for incremental performance gains in thin-film photovoltaic devices.
