Characterizing the Efficiency of Perovskite Solar Cells and Light-Emitting Diodes

Metal halide perovskites (MHPs) are being widely studied as a light-absorber for high-efficiency solar cells. With efforts being made throughout the globe, the power conversion efficiency of MHP solar cells has recently soared up to 25.2%. MHPs are now being spotlighted as a next-generation light-emitter as well. Their high color purity and solution-processability are of particular interest for display applications, which in general benefit from wide color gamut and low-cost high-resolution subpixel patterning. For this reason, research activities on perovskite light-emitting diodes (LEDs) are rapidly growing, and their external quantum efficiencies have been dramatically improved to over 20%. As more and more research groups with different backgrounds are working on these perovskite optoelectronic devices, the demand is growing for standard methods for accurate efficiency measurement that can be agreed upon across the disciplines and, at the same time, can be realized easily in the lab environment with due diligence. Herein, optoelectronic characterization methods are revisited from the viewpoint of MHP solar cells and LEDs. General efficiency measurement practices are first reviewed, common sources of errors are introduced, and guidelines for avoiding or minimizing those errors are then suggested to help researchers in fields develop the best measurement practice. Metal halide perovskite (MHP)-based solar cells and light-emitting diodes (LEDs) have shown a great potential to compete with the conventional optoelectronic devices such as silicon, gallium-arsenide-based inorganic solar cells, and organic LEDs. MHPs have been widely studied as a light-absorbing material for high-efficiency solar cells due to their high charge-carrier mobility and direct band gap leading to large absorption coefficient. Also, MHPs provide benefits of wide color gamut and low fabrication cost for display applications due to their high color purity and solution processability. There are features specific to MHP-based solar cell and LED devices that make accurate measurement of their device efficiency challenging or at least tricky. In the context, optoelectronic characterization methods and common sources of errors are reviewed, and accurate measurement guidelines for device efficiencies in a viewpoint of MHP-based solar cells and LEDs are suggested. The guidelines would improve the reliability in the uprising research on MHP-based solar cells and LEDs, helping researches in the fields develop the best measurement practice. As the device efficiency of metal halide perovskite (MHP)-based solar cells and light-emitting diodes (LEDs) has been dramatically increased in the recent few years, accurate characterization of the efficiency has become a very important issue for the reliability of the research field. In this perspective, general efficiency measurement practices and common sources of errors introduced in MHP-based solar cells and LEDs are reviewed, and guidelines for the best measurement practices to avoid or minimize erroneous efficiency characterizations are provided.