Proceedings of nanoGe Fall Meeting19 (NFM19)
Publication date: 18th July 2019
Title: 2D Hybrid Organic-Inorganic Metal Halide Perovskite Nanowires
Bapi Pradhan* and Johan Hofkens
Molecular Imaging and Photonics, Department of Chemistry, KU Leuven
*bapi.pradhan@kuleuven.be
Solution-processed metal halide perovskites have shown tremendous potential in high-performance light-harvesting, generation, photodetectors and photocatalysis applications realized within a short span of time. Low-cost earth-abundant precursors, low-temperature film annealing and solution processability make them an attractive candidate for next-generation optoelectronics. A 3D perovskite with a chemical formula of ABX3 (where A is CH3NH3+, Cs+; B is Pb, Sn and X are halogens) have shown solar cell power conversion efficiency exceeding 24%.[1] One of the major shortcomings of the 3D perovskites is ambient and thermal stability. Recent development has shown that intercalation of larger organic cations into 3D CH3NH3PbI3 reduces the perovskite dimensionality to 2D/3D structure.[2,3] The 2D/3D structures are much less susceptible towards oxygen and moistures, making them much more stable through the hydrophobicity of bulky organic cation. On the other hand, nanocrystals metal halide perovskite offers ease of solution processability over a large number of particle shape, size, and crystal structure for optoelectronic devices.[4-6] We have developed the synthesis of formamidinium and guanidinium lead iodide 2D perovskites nanowires at room temperature by ligand assisted re-precipitation method. Long-chain alkyl acid and alkyl amine surface ligand ratio play a major role in tuning the aspect ratio of these nanowires. Photophysics analysis shows that the red emission of these nanowires arises due to the presence of self-trapped exciton (STEs). Low-temperature photoluminescence (PL) measurement shows strong exciton-phonon coupling. Nonlinear optics measurement reveals two-photon photoluminescence, third harmonic generations and four-wave mixing which has been confirmed by laser powder dependent measurements. These nanowires show photocurrent upon illumination. Photo-switching of these nanowires confirms device reproducibly and stability of these materials for a longer time. The stable and repeatable photoswitching properties are suggestive that these nanowires as a potential optoelectronic material.
References:
1. https://www.nrel.gov/pv/cell-efficiency.html
2. Smith et al, “A Layered Hybrid Perovskite Solar‐Cell Absorber with Enhanced Moisture Stability” Angew. Chem., 2014, 126, 11414–11417.
3. Tsai et al., “High-efficiency two-dimensional Ruddlesden–Popper perovskite solar cells” Nature 2016, 536, 312–316.
4. Protesescu et. al. “Nanocrystals of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, and I): Novel Optoelectronic Materials Showing Bright Emission with Wide Color Gamut” Nano Lett. 2015, 15,3692-3696.
5. Pradhan, et al. “Size Tunable Cesium Antimony Chloride Perovskite Nanowires and Nanorods” Chem. Mater. 2018, 30, 2135-2142.
6. Pradhan et. al. “Postsynthesis Spontaneous Coalescence of Mixed-Halide Perovskite Nanocubes into Phase-Stable Single-Crystalline Uniform Luminescent Nanowires” J. Phys. Chem. Lett. 2019, 10, 1805-1812.
KU Leuven
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