Enhanced Silicon Photovoltaic Efficiency by Solar Light Spectral Modulation via Photonically Tuned Porphyrin-Iron Oxide Hybrid Thin Films

The temperature dependency of photovoltaic power conversion efficiency (PCE) has been a key challenge to solar applications due to intrinsic processes. Herein, an alternative strategy is developed by modulating the solar light spectrum with a series of photonic hybrids. Transparent thin films are synthesized with the solutions of porphyrin compounds and iron oxides which exhibit strong absorptions in the UV and IR regions. These spectral modulating thin films are photonically tuned via compositional optimization to absorb photons near 400 nm and above 1127 nm from solar spectrum to reduce thermalization and sub-bandgap absorption. These spectral modulators are applied in a particular configuration above a commercial silicon panel to partially filter the simulated solar light. The PCE of the silicon panel suffers a significant decrease due to temperature increase from 22.9 to 92.9 degrees C after 60 min solar irradiation, resulting in a PCE decrease from 25.1% to 16.3%. With the transparent spectral modulators, upon solar irradiation for 60 min, the maximum PCE has maintained at 20.5%. The mechanisms of PCE enhancement are identified based on reduced thermalization and sub-bandgap absorption.