Photon energy loss and management in perovskite solar cells

The power conversion efficiency (PCE) of perovskite solar cells (PSCs) has increased rapidly to 25.7% in 2022. There is growing curiosity about whether it will increase further up to the PCE limit. Understanding the fundamental energy loss mechanism and targeted treatment is the crux to step forward, especially the definite and management of photons in PSCs. Here, we first briefly review the main modes of photon energy loss in PSCs and illustrate the significance of photon recycling. Next, historical research trials to overcome these loss mechanisms in PSCs are highlighted, including the application of anti-reflection coatings, plasmonic strategies, and the adoption of upconversion and downconversion materials. Finally, we make a brief summary and prospect about strategies that can help to improve photon management in the future.