The Cost of Quantum Yield
John R. Swierk
Abstract
The quantum yield (QY) of a photocatalytic reaction significantly influences its performance, as reactions with low QYs require more intense light sources and longer illumination times to achieve efficient reaction rates. Unfortunately, the importance of QY is often overlooked in the design of photocatalytic reactions for small-molecule synthesis, leading to potential cost implications and reduced productivity. This study examines various photochemical reactor designs from the literature to estimate photon flux and light generation costs and investigates the impact of QY on both cost and productivity. The findings reveal substantial penalties in cost and productivity when QYs are low. For instance, external QYs below 1% can result in significant light generation costs and maximum productivities of less than 1 mol of product per day. Moreover, the study highlights that high QYs have a larger effect on potential productivity than high product yields. By optimizing for QY instead of product yield, kinetic and revenue modeling for the photoredox-mediated synthesis of ceralasertib demonstrate the potential for generating hundreds of thousands of dollars in additional revenue per day. Overall, this work emphasizes the need for increased consideration of QY in the design of photocatalytic reactions.