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Taylor EJ, Iyer V, Dhami BS, Klein C, Lawrie BJ, Appavoo K. Hyperspectral mapping of nanoscale photophysics and degradation processes in hybrid perovskite at the single grain level. NANOSCALE ADVANCES 2023; 5:4687-4695. [PMID: 37705772 PMCID: PMC10496886 DOI: 10.1039/d3na00529a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 08/14/2023] [Indexed: 09/15/2023]
Abstract
With solar cells reaching 26.1% certified efficiency, hybrid perovskites are now the most efficient thin film photovoltaic material. Though substantial effort has focussed on synthesis approaches and device architectures to further improve perovskite-based solar cells, more work is needed to correlate physical properties of the underlying film structure with device performance. Here, using cathodoluminescence microscopy coupled with unsupervised machine learning, we quantify how nanoscale heterogeneity globally builds up within a large morphological grain of hybrid perovskite when exposed to extrinsic stimuli such as charge accumulation from electron beams or milder environmental factors like humidity. The converged electron-beam excitation allows us to map PbI2 and the emergence of other intermediate phases with high spatial and energy resolution. In contrast with recent reports of hybrid perovskite cathodoluminescence, we observe no significant change in the PbI2 signatures, even after high-energy electron beam excitation. In fact, we can exploit the stable PbI2 signatures to quantitatively map how hybrid perovskites degrade. Moreover, we show how our methodology allows disentangling of the photophysics associated with photon recycling and band-edge emission with sub-micron resolution using a fundamental understanding of electron interactions in hybrid perovskites.
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Affiliation(s)
- Ethan J Taylor
- Department of Physics, University of Alabama at Birmingham 1300 University Blvd., Birmingham AL 35294 USA
| | - Vasudevan Iyer
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory Oak Ridge TN 37831 USA
| | - Bibek S Dhami
- Department of Physics, University of Alabama at Birmingham 1300 University Blvd., Birmingham AL 35294 USA
| | - Clay Klein
- Clarion University 840 Wood St, Clarion PA 16214 USA
| | - Benjamin J Lawrie
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory Oak Ridge TN 37831 USA
- Materials Science and Technology Division, Oak Ridge National Laboratory Oak Ridge TN 37831 USA
| | - Kannatassen Appavoo
- Department of Physics, University of Alabama at Birmingham 1300 University Blvd., Birmingham AL 35294 USA
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Levy S, Be'er O, Veber N, Monachon C, Bekenstein Y. Tuning the Colloidal Softness of CsPbBr 3 Nanocrystals for Homogeneous Superlattices. NANO LETTERS 2023; 23:7129-7134. [PMID: 37470186 DOI: 10.1021/acs.nanolett.3c02023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/21/2023]
Abstract
Perovskite nanocrystal superlattices (NC SLs), made from millions of ordered crystals, support collective optoelectronic phenomena. Coupled NC emitters are highly sensitive to the structural and spectral inhomogeneities of the NC ensemble. Free electrons in scanning electron microscopy (SEM) are used to probe the cathodoluminescence (CL) properties of CsPbBr3 SLs with a ∼20 nm spatial resolution. Correlated CL-SEM measurements allow for simultaneous characterization of structural and spectral heterogeneities of the SLs. Hyperspectral CL mapping shows multipole emissive domains within a single SL. Consistently, the edges of the SLs are blue-shifted relative to the central domain by up to 65 meV. We discover a relation between NC building block colloidal softness and the extent of the CL shift. Residual uniaxial compressive strains accompanying SL formation are contributors to these emission shifts. Therefore, precise control over the colloidal softness of the NC building blocks is critical for SL engineering.
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Affiliation(s)
- Shai Levy
- Department of Materials Science and Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Orr Be'er
- Department of Materials Science and Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Noam Veber
- Department of Materials Science and Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
- The Solid-State Institute, Technion - Israel Institute of Technology, 32000 Haifa, Israel
| | - Christian Monachon
- Attolight SA, EPFL Innovation Park, Building D, 1015 Lausanne, Switzerland
| | - Yehonadav Bekenstein
- Department of Materials Science and Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
- The Solid-State Institute, Technion - Israel Institute of Technology, 32000 Haifa, Israel
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Piotrowski M, Ge Z, Wang Y, Bandela AK, Thumu U. Programmable precise kinetic control over crystal phase, size, and equilibrium in spontaneous metathesis reaction for Cs-Pb-Br nanostructure patterns at room temperature. NANOSCALE 2022; 14:16806-16815. [PMID: 36300506 DOI: 10.1039/d2nr04102b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Growth kinetics involved in spontaneous random clustering of perovskite precursors to a particular cesium-lead-bromide (Cs-Pb-Br) nanocrystal (NC) is a poorly understood phenomenon and its spectroscopic investigation is highly challenging. There is scarcely any method that has been optimized yet in which perovskites and their related NCs of a particular size can be grown, viewed, or tuned to another by reaction handling. Here, for the first time, we shed light on the largely overlooked process of growth kinetics of these transformations throughout the reaction trajectory of anionic [PbBrx]n- crystallization dictated by Cs+ cation and report a simple and direct approach to control the metathesis reaction between two precursors (specifically Cs+- and PbBr2-associated oligomeric complexes) in one solvent at room temperature to monitor the NC growth characteristics in a stepwise manner even in the early stages of nucleation. Altering the molar ratio of the two precursors up to a factor of 10 leads to the formation of three prominent phases (CsPbBr3, Cs4PbBr6, CsBr) as dictated by Cs+ to trigger distinct morphological forms (nanobelts, nanoplatelets, rhombohedral NCs, pseudo-rhombic NCs, spherical CsBr NCs, cubic CsBr NCs) including a transient phase that is formed out of linearly self-assembled CsPbBr3 clusters. Our results pave the way towards understanding spontaneous crystallization to develop well-defined, hassle-free routes for diverse perovskite NCs in a simple yet controlled manner.
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Affiliation(s)
- Marek Piotrowski
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China.
| | - Zhongsheng Ge
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China.
| | - Yixi Wang
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China.
| | - Anil Kumar Bandela
- Department of Chemistry, Ben Gurion University of the Negev Beer, Sheva 84105, Israel.
| | - Udayabhaskararao Thumu
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China.
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Zhou C, Huang Y, Zhang Y, Lu B, Xu Y, Ye Q, Yang X, Zhong J, Tang JX, Mao H. CsPbBr 3 microarrays with tunable periodicity, optoelectronic and field emission properties using self-assembled polystyrene template and co-evaporation method. Phys Chem Chem Phys 2022; 24:13210-13216. [PMID: 35593393 DOI: 10.1039/d2cp00955b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The booming growth of all inorganic cesium lead halide perovskites in optoelectronic applications has prompted extensive research interest in the fabrication of ordered nanostructures or microarrays for enhanced device performances. However, the high cost and complexity of commercial lithographic approaches impede the facile fabrication of perovskite microarrays. Herein, CsPbBr3 microarrays with tunable periodicities have been fabricated using a self-assembled polystyrene nanosphere template and a co-evaporation method. The periodicity of CsPbBr3 microarrays is precisely manipulated by simply modifying the size of polystyrene nanospheres. These microarrays are beneficial for light harvesting, leading to better light absorption ability and prolonged photoinduced carrier lifetime. The longest average carrier lifetime of 58.3 ns is obtained for CsPbBr3 microarrays with a periodicity of 1.0 μm. More importantly, the periodic structures of CsPbBr3 microarrays result in a tunable density of emitter tips in field emission devices. Compared to compact CsPbBr3 films, a 68.2% decrease of the turn-on field is observed for CsPbBr3 microarrays when the periodicity is 150 nm. The higher density of emitter tips leads to larger local field enhancement, and hence the largest field enhancement factor of 3346.6. Finally, a good emission current stability for CsPbBr3 microarray-based field emission devices has been demonstrated.
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Affiliation(s)
- ChunWei Zhou
- School of Physics, Hangzhou Normal University, Hangzhou 311121, P. R. China.
| | - Yu Huang
- School of Physics, Hangzhou Normal University, Hangzhou 311121, P. R. China.
| | - YinLong Zhang
- School of Physics, Hangzhou Normal University, Hangzhou 311121, P. R. China.
| | - Bin Lu
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, P. R. China
| | - YiFeng Xu
- School of Physics, Hangzhou Normal University, Hangzhou 311121, P. R. China.
| | - QuanLin Ye
- School of Physics, Hangzhou Normal University, Hangzhou 311121, P. R. China.
| | - XuXin Yang
- School of Physics, Hangzhou Normal University, Hangzhou 311121, P. R. China.
| | - JianQiang Zhong
- School of Physics, Hangzhou Normal University, Hangzhou 311121, P. R. China.
| | - Jian-Xin Tang
- School of Physics, Hangzhou Normal University, Hangzhou 311121, P. R. China. .,Institute of Functional Nano & Soft Materials (FUNSOM), Collaborative Innovation Centre of Suzhou Nano Science & Technology, Soochow University, Suzhou 215123, Jiangsu, P. R. China
| | - HongYing Mao
- School of Physics, Hangzhou Normal University, Hangzhou 311121, P. R. China.
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