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Narra S, Liao PS, Bhosale SS, Diau EWG. Effect of Acidic Strength of Surface Ligands on the Carrier Relaxation Dynamics of Hybrid Perovskite Nanocrystals. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:nano13111718. [PMID: 37299621 DOI: 10.3390/nano13111718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 05/15/2023] [Accepted: 05/19/2023] [Indexed: 06/12/2023]
Abstract
Perovskite nanocrystals (PeNCs) are known for their use in numerous optoelectronic applications. Surface ligands are critical for passivating surface defects to enhance the charge transport and photoluminescence quantum yields of the PeNCs. Herein, we investigated the dual functional abilities of bulky cyclic organic ammonium cations as surface-passivating agents and charge scavengers to overcome the lability and insulating nature of conventional long-chain type oleyl amine and oleic acid ligands. Here, red-emitting hybrid PeNCs of the composition CsxFA(1-x)PbBryI(3-y) are chosen as the standard (Std) sample, where cyclohexylammonium (CHA), phenylethylammonium (PEA) and (trifuluoromethyl)benzylamonium (TFB) cations were chosen as the bifunctional surface-passivating ligands. Photoluminescence decay dynamics showed that the chosen cyclic ligands could successfully eliminate the shallow defect-mediated decay process. Further, femtosecond transient absorption spectral (TAS) studies uncovered the rapidly decaying non-radiative pathways; i.e., charge extraction (trapping) by the surface ligands. The charge extraction rates of the bulky cyclic organic ammonium cations were shown to depend on their acid dissociation constant (pKa) values and actinic excitation energies. Excitation wavelength-dependent TAS studies indicate that the exciton trapping rate is slower than the carrier trapping rate of these surface ligands.
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Affiliation(s)
- Sudhakar Narra
- Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu 300093, Taiwan
- Center of Emergent Functional Matter Science, National Yang Ming Chiao Tung University, Hsinchu 300093, Taiwan
| | - Po-Sen Liao
- Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu 300093, Taiwan
| | - Sumit S Bhosale
- Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu 300093, Taiwan
| | - Eric Wei-Guang Diau
- Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu 300093, Taiwan
- Center of Emergent Functional Matter Science, National Yang Ming Chiao Tung University, Hsinchu 300093, Taiwan
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Tsai IH, Narra S, Bhosale SS, Diau EWG. Energy and Charge Transfer Dynamics in Red-Emitting Hybrid Organo-Inorganic Mixed Halide Perovskite Nanocrystals. J Phys Chem Lett 2023; 14:2580-2587. [PMID: 36880907 DOI: 10.1021/acs.jpclett.3c00333] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
We report time-resolved spectral properties of highly stable and efficient red-emitting hybrid perovskite nanocrystals with the composition FA0.5MA0.5PbBr0.5I2.5 (FAMA PeNC) synthesized by using the hot-addition method. The PL spectrum of the FAMA PeNC shows a broad asymmetric band covering 580 to 760 nm with a peak at 690 nm which can be deconvoluted into two bands corresponding to the MA and FA domains. The interactions between the MA and FA domains are shown to affect the relaxation dynamics of the PeNCs from the subpicosecond to tens of nanoseconds scale. Time-correlated single-photon counting (TCSPC), femtosecond PL optical gating (FOG), and femtosecond transient absorption spectral (TAS) techniques were employed to study the intercrystal energy transfer (photon recycling) and intracrystal charge transfer processes between the MA and the FA domains of the crystals. These two processes are shown to increase the radiative lifetimes for the PLQYs exceeding 80%, which may play a key role in enhancing the performance of PeNC-based solar cells.
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Chen YH, Tsai KA, Liu TW, Chang YJ, Wei YC, Zheng MW, Liu SH, Liao MY, Sie PY, Lin JH, Tseng SW, Pu YC. Charge Carrier Dynamics of CsPbBr 3/g-C 3N 4 Nanoheterostructures in Visible-Light-Driven CO 2-to-CO Conversion. J Phys Chem Lett 2023; 14:122-131. [PMID: 36574643 DOI: 10.1021/acs.jpclett.2c03474] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The photon energy-dependent selectivity of photocatalytic CO2-to-CO conversion by CsPbBr3 nanocrystals (NCs) and CsPbBr3/g-C3N4 nanoheterostructures (NHSs) was demonstrated for the first time. The surficial capping ligands of CsPbBr3 NCs would adsorb CO2, resulting in the carboxyl intermediate to process the CO2-to-CO conversion via carbene pathways. The type-II energy band structure at the heterojunction of CsPbBr3/g-C3N4 NHSs would separate the charge carriers, promoting the efficiency in photocatalytic CO2-to-CO conversion. The electron consumption rate of CO2-to-CO conversion for CsPbBr3/g-C3N4 NHSs was found to intensively depend on the rate constant of interfacial hole transfer from CsPbBr3 to g-C3N4. An in situ transient absorption spectroscopy investigation revealed that the half-life time of photoexcited electrons in optimized CsPbBr3/g-C3N4 NHS was extended two times more than that in the CsPbBr3 NCs, resulting in the higher probability of charge carriers to carry out the CO2-to-CO conversion. The current work presents important and novel insights of semiconductor NHSs for solar energy-driven CO2 conversion.
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Affiliation(s)
- Yu-Hung Chen
- School of Medicine, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan
| | - Kai-An Tsai
- Department of Materials Science, National University of Tainan, Tainan 70005, Taiwan
| | - Tzu-Wei Liu
- Department of Materials Science, National University of Tainan, Tainan 70005, Taiwan
| | - Yao-Jen Chang
- Department of Materials Science, National University of Tainan, Tainan 70005, Taiwan
| | - Yu-Chen Wei
- Department of Materials Science, National University of Tainan, Tainan 70005, Taiwan
| | - Meng-Wei Zheng
- Department of Environmental Engineering, National Cheng Kung University, Tainan 70101, Taiwan
| | - Shou-Heng Liu
- Department of Environmental Engineering, National Cheng Kung University, Tainan 70101, Taiwan
| | - Mei-Yi Liao
- Department of Applied Chemistry, National Pingtung University, Pingtung City 900, Pingtung, Taiwan
| | - Pei-Yu Sie
- Department of Applied Chemistry, National Pingtung University, Pingtung City 900, Pingtung, Taiwan
| | - Jarrn-Horng Lin
- Department of Materials Science, National University of Tainan, Tainan 70005, Taiwan
| | - Shih-Wen Tseng
- Core Facility Center, National Cheng Kung University, Tainan 70101, Taiwan
| | - Ying-Chih Pu
- Department of Materials Science, National University of Tainan, Tainan 70005, Taiwan
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