Semitransparent Organic Photovoltaics with High Average Visible Transmittance

Organic Photovoltaics (OPVs) offer sustainable, solution-processable, and cost-effective energy harvesting solutions. While opaque devices underwent enormous progress in the past decade, it remains a challenge to meet the high transparency requirements for integrated semitransparent OPVs (ST-OPVs) for buildings, skylights, skyscrapers, or greenhouses. In this work, we investigate the charge generation-recombination dynamics in three semitransparent blend systems with varied donor concentrations to understand the performance limitations. We also study the effect of the optical expediency of Au, Ag, Al, and graphite as back electrode material on ST-OPVs and show that ‘one size fits all’ is not a valid approach for choosing the back electrode material. It is important to consider the active layer absorption, active layer thickness and application in selecting the back electrode material. We demonstrate that using the dilute donor approach with an appropriate back electrode can yield devices with 73 % average visible transmittance.