Spectral Engineering of Semitransparent Polymer Solar Cells for Greenhouse Applications

In this study, a wavelength selective semitransparent polymer solar cell (ST-PSC) with a proper transmission spectrum for plant growth is proposed for greenhouse applications. A ternary strategy combining a wide bandgap polymer donor with a near-infrared absorbing nonfullerene acceptor and a high electron mobility fullerene acceptor is introduced to achieve PSCs with power conversion efficiency (PCE) over 10%. The addition of PC71BM into J52:IEICO-4F binary blend contributes to the suppressed trap-assisted recombination, enhanced charge extraction, and improved open-circuit voltage simultaneously. ST-PSC based on the J52:IEICO-4F:PC71BM ternary blend shows an optimized performance with PCE of 7.75% and a defined crop growth factor of 24.8%. Such high-performance ST-PSC is achieved by carefully engineering the absorption spectrum of the light harvesting materials. As a result, the transmission spectra of the semitransparent devices are well-matched with the absorption spectra of the photoreceptors, such as chlorophylls, in green plants, which provides adequate lighting conditions for photosynthesis and plant growth, and therefore making it a competitive candidate for photovoltaic greenhouse applications.