Solar photons beyond the band gap wavelengths: their effect on solution-processed solar cells

A deep understanding of how solution-processed solar cells (SSCs) perform under varying temperatures and irradiance is crucial for their optimal design, synthesis, and use. However, current partial spectral characterization, primarily below the band gap wavelengths (<i>λ</i> < <i>λ</i>_g), limits insights into their full operation. In this work, we expand the current knowledge by providing comprehensive full-spectrum experimental optical characterizations (∼300-2500 nm) and theoretical optical-thermal-electrical analysis for the most common high-efficiency single-junction and tandem organic SSCs (OSCs) and perovskite SSCs (PSCs), including p-i-n OSC, n-i-p OSC, p-i-n PSC, n-i-p mesoscopic PSC, OSC/PSC, and PSC/PSC. By incorporating solar photons above <i>λ</i>_g in our investigation, we uncover the effects of parasitic absorption (∼300-2500 nm) and conversion losses (<i>λ</i> < <i>λ</i>_g) on operating temperature and power conversion efficiency (PCE) losses, highlighting the conditions, materials, and optimal architectures for reducing device temperature. These improvements could reduce PCE losses by up to ∼7 times compared to conventional silicon wafer-based solar cells in real-world conditions.