Perovskite Cell-to-Module Efficiency Gap: Why Large Areas Lose Efficiency

… more less The perovskite cell-to-module gap is the drop in efficiency when a lab cell becomes a large panel. Record cells are often about a tenth of a square centimetre, smaller than a fingernail. A module can be thousands of times larger, and several losses grow with size. First, the film is harder to keep even. One pinhole lets the top and bottom electrodes touch, which shunts a whole strip. Second, the clear electrode has sheet resistance, so current loses voltage as it travels across it. Both of these show up as a lower fill factor on the J-V curve. Third, scribes and edge deletion, the bare border kept for the seal, add area that makes no power. Fourth, one weak strip limits the current of every strip in series with it. To compare numbers fairly, check the area. Active area counts only the parts that make power. Aperture area counts the whole open window, dead lines included, and gives a lower and more honest number. Also check the size class: cell, mini-module or full module. A large gap between them points to a film or scribing problem, not a poor material. After this Concept you can read a reported efficiency, find its area and size class, and judge how far it is from a real panel.