《Nature Communications》Hairen Tan's team at Nanjing University - Innovative conversion technique significantly improves power conversion efficiency of wide bandgap perovskite solar cells to 19.6%
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- Light-induced halide segregation limits the power conversion efficiency and stability of wide bandgap perovskite solar cells. Using solution post-treatment to form a mixed 2D/3D heterostructure is a typical strategy to improve the efficiency and stability of perovskite solar cells.
- However, due to the composition-dependent surface reconstruction, conventional solution post-treatment is not applicable for wide bandgap perovskite solar cells lacking methylammonium and enriched in cesium/bromide.
- Researchers have developed a universal 3D-to-2D perovskite conversion technique to preferentially grow 2D structures with higher dimensionality (n ≥ 2) atop wide bandgap perovskite layers (1.78 eV).
- This technique first deposits a uniform 3D MAPbI3 thin layer through a vapor-assisted two-step deposition process, then converts it into a 2D structure. This 2D/3D heterostructure suppresses light-induced halide segregation, reduces non-radiative interfacial recombination, and facilitates charge extraction.
- The wide bandgap perovskite solar cells achieved a power conversion efficiency of 19.6% and an open-circuit voltage of 1.32 V. When coupled with thermally stable narrow bandgap FAPb0.5Sn0.5I3 perovskites, the all-perovskite tandem solar cells attained a stabilized power conversion efficiency of 28.1% and maintained 90% of initial performance after continuous 1-sun illumination for 855 hours.
Measurements in this study were performed using Enlitech QE-R products.
Major Breakthrough in Perovskite Solar Cell Research
A recent study on perovskite solar cells has achieved a major breakthrough. Researchers have significantly improved the power conversion efficiency and long-term stability of perovskite solar cells using innovative techniques.
Light-Induced Halide Segregation Limits Efficiency
Previous studies have found that light exposure causes halide segregation in the perovskite material, which limits the efficiency and stability of solar cells. Surface treatment with solutions is a common approach to enhance the performance of solar cells. However, conventional solution treatment is not ideal for certain compositions of perovskite materials.
Development of a Universal Conversion Technique
To address this challenge, the research team developed a universal technique to convert three-dimensional perovskites into two-dimensional structures. They first deposited a uniform three-dimensional thin layer on the perovskite surface, then converted it into a two-dimensional structure. This 2D/3D heterostructure effectively suppresses light-induced halide segregation.
Significant Improvements in Efficiency and Stability
Applying this technique, the power conversion efficiency of wide bandgap perovskite solar cells reached 19.6% and the open-circuit voltage reached 1.32 V, both record highs. When coupled with other perovskite materials, the efficiency of all-perovskite tandem solar cells can reach 28.1% with excellent long-term stability.
Research Opens New Avenues
The research results were published in a top academic journal. The researchers noted that this universal conversion technique paves the way for the development of wide bandgap perovskite solar cells, and will significantly promote their commercialization. The findings will provide important support for the further advancement of renewable energy.
a, b Device structure of Cs0.2FA0.8Pb(I0.6Br0.4)3 PSCs for photostability study under a open-circuit and b short-circuit conditions. c, d J–V curves evolution of WBG device under illumination at c open-circuit and d MPP tracking conditions. e, f PL spectra of perovskite device under illumination at e open-circuit and f short-circuit conditions. The samples were excited under a 532 nm laser for 10 min. The insets show schematic illustrations of band alignments in devices under illumination at open-circuit and short-circuit conditions. CBM conduction band minimum, VBM valence band maximum, EF,N electron quasi-fermi level, EF,P hole quasi-fermi level.
a J–V curves from control, standard-2D, and VAQ-2D-treated Cs0.2FA0.8Pb(I0.6Br0.4)3 devices. b PCE distribution of VAQ-2D-treated devices. c EQE curves of WBG devices with standard-2D or quasi-2D passivation. J–V curves of the champion VAQ-2D device with different bandgaps. d J–V curves from control, standard-2D and VAQ-2D-treated DMA0.1Cs0.4FA0.5Pb(I0.72Br0.24Cl0.04)3 devices. e MPP tracking was measured with the encapsulated control and VAQ-2D devices under full solar illumination (AM 1.5 G, 100 mW cm−2) in ambient conditions. f, g PCE and detailed parameters evolution of the encapsulated control and VAQ-2D devices measured at open-circuit conditions under full solar illumination (AM 1.5 G, 100 mW cm−2) in ambient air. The error bars represent the standard deviation of the PCE measured from five devices.