| 1. |
- Ning, Weihua, et al.
(author)
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Long Electron-Hole Diffusion Length in High-Quality Lead-Free Double Perovskite Films
- 2018
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In: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 30:20
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Journal article (peer-reviewed)abstract
- Developing environmentally friendly perovskites has become important in solving the toxicity issue of lead-based perovskite solar cells. Here, the first double perovskite (Cs2AgBiBr6) solar cells using the planar structure are demonstrated. The prepared Cs2AgBiBr6 films are composed of high-crystal-quality grains with diameters equal to the film thickness, thus minimizing the grain boundary length and the carrier recombination. These high-quality double perovskite films show long electron-hole diffusion lengths greater than 100 nm, enabling the fabrication of planar structure double perovskite solar cells. The resulting solar cells based on planar TiO2 exhibit an average power conversion efficiency over 1%. This work represents an important step forward toward the realization of environmentally friendly solar cells and also has important implications for the applications of double perovskites in other optoelectronic devices.
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| 2. |
- Ning, Weihua, et al.
(author)
-
Thermochromic Lead-Free Halide Double Perovskites
- 2019
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In: Advanced Functional Materials. - : WILEY-V C H VERLAG GMBH. - 1616-301X .- 1616-3028. ; 29:10
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Journal article (peer-reviewed)abstract
- Lead-free halide double perovskites with diverse electronic structures and optical responses, as well as superior material stability show great promise for a range of optoelectronic applications. However, their large bandgaps limit their applications in the visible light range such as solar cells. In this work, an efficient temperature-derived bandgap modulation, that is, an exotic fully reversible thermochromism in both single crystals and thin films of Cs2AgBiBr6 double perovskites is demonstrated. Along with the thermochromism, temperature-dependent changes in the bond lengths of Ag Symbol of the Klingon Empire Br (R-Ag Symbol of the Klingon Empire Br) and Bi Symbol of the Klingon Empire Br (R-Bi Symbol of the Klingon Empire Br) are observed. The first-principle molecular dynamics simulations reveal substantial anharmonic fluctuations of the R-Ag Symbol of the Klingon Empire Br and R-Bi Symbol of the Klingon Empire Br at high temperatures. The synergy of anharmonic fluctuations and associated electron-phonon coupling, and the peculiar spin-orbit coupling effect, is responsible for the thermochromism. In addition, the intrinsic bandgap of Cs2AgBiBr6 shows negligible changes after repeated heating/cooling cycles under ambient conditions, indicating excellent thermal and environmental stability. This work demonstrates a stable thermochromic lead-free double perovskite that has great potential in the applications of smart windows and temperature sensors. Moreover, the findings on the structure modulation-induced bandgap narrowing of Cs2AgBiBr6 provide new insights for the further development of optoelectronic devices based on the lead-free halide double perovskites.
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| 3. |
- Yang, Jie, et al.
(author)
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Stable, High-Sensitivity and Fast-Response Photodetectors Based on Lead-Free Cs2AgBiBr6 Double Perovskite Films
- 2019
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In: Advanced Optical Materials. - : WILEY-V C H VERLAG GMBH. - 2162-7568 .- 2195-1071. ; 7:13
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Journal article (peer-reviewed)abstract
- Solution-processed metal halide perovskites (MHPs) have demonstrated great advances on achieving high-performance photodetectors. However, the intrinsic material instability and the toxicity of lead still hinder the practical applications of MHPs-based photodetectors. In this work, the first highly sensitive and fast-response lead-free perovskite photodetectors based on Cs2AgBiBr6 double perovskite films are demonstrated. A convenient solution method is developed to deposit high-quality Cs2AgBiBr6 film with large grain sizes, low trap densities, and long charge carrier lifetimes. Incorporated within a photodiode device architecture comprised of optimized hole- and electron-transporting layers, lead-free perovskite photodetectors are achieved exhibiting a high detectivity of 3.29 x 10(12) Jones, a large linear dynamic range of 193 dB, and a fast response time of approximate to 17 ns. All the key figures of merit of the devices are comparable with the reported best-performing photodetectors based on lead halide perovskites. In addition, the resulting devices exhibit excellent thermal and environmental stability. The nonencapsulated devices show negligible degradation after thermal stressing at 150 degrees C and less than 5% degradation in the photoresponsivity after storage in ambient air for approximate to 2300 h. The results demonstrate the great potential of the lead-free Cs2AgBiBr6 double perovskite in applications for environmentally friendly and high-performance photodetectors.
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