Light Absorption and Recycling in Hybrid Metal Halide Perovskite Photovoltaic Devices

• Published in: Advanced energy materials 2020-03, Vol.10 (10), p.n/a
• Main Authors: Patel, Jay B., Wright, Adam D., Lohmann, Kilian B., Peng, Kun, Xia, Chelsea Q., Ball, James M., Noel, Nakita K., Crothers, Timothy W., Wong‐Leung, Jenny, Snaith, Henry J., Herz, Laura M., Johnston, Michael B.
• Format: Article
• Language: English
• Subjects: Charge transport; Devices; Electrical properties; Electromagnetic absorption; Energy conversion efficiency; Interference; light management; Metal halides; Optical properties; Optimization; Perovskites; photon reabsorption; Photons; Photovoltaic cells; quantum efficiency; Solar cells; Thickness; thickness dependence; Transport properties; vapor deposition
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.201903653

The production of highly efficient single‐ and multijunction metal halide perovskite (MHP) solar cells requires careful optimization of the optical and electrical properties of these devices. Here, precise control of CH3NH3PbI3 perovskite layers is demonstrated in solar cell devices through the use of dual source coevaporation. Light absorption and device performance are tracked for incorporated MHP films ranging from ≈67 nm to ≈1.4 µm thickness and transfer‐matrix optical modeling is utilized to quantify optical losses that arise from interference effects. Based on these results, a device with 19.2% steady‐state power conversion efficiency is achieved through incorporation of a perovskite film with near‐optimum predicted thickness (≈709 nm). Significantly, a clear signature of photon reabsorption is observed in perovskite films that have the same thickness (≈709 nm) as in the optimized device. Despite the positive effect of photon recycling associated with photon reabsorption, devices with thicker (>750 nm) MHP layers exhibit poor performance owing to competing nonradiative charge recombination in a “dead‐volume” of MHP. Overall, these findings demonstrate the need for fine control over MHP thickness to achieve the highest efficiency cells, and accurate consideration of photon reabsorption, optical interference, and charge transport properties. Precise thickness control of metal halide perovskite layers in solar cells is achieved using thermal coevaporation. The perovskite layer thickness over a range from 67 nm to 1.4 µm is found to have a significant impact on the power conversion efficiency of solar cells owing to its influence on optical interference, photon‐reabsorption, and charge collection properties of the device.