Effect of Acidic Strength of Surface Ligands on the Carrier Relaxation Dynamics of Hybrid Perovskite Nanocrystals
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 bu...
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MDPI AG
2023-05-01
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| Series: | Nanomaterials |
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| author | Sudhakar Narra Po-Sen Liao Sumit S. Bhosale Eric Wei-Guang Diau |
| author_facet | Sudhakar Narra Po-Sen Liao Sumit S. Bhosale Eric Wei-Guang Diau |
| author_sort | Sudhakar Narra |
| collection | DOAJ |
| description | 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 Cs<sub>x</sub>FA<sub>(1−x)</sub>PbBr<sub>y</sub>I<sub>(3−y)</sub> 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. |
| first_indexed | 2024-03-11T03:00:43Z |
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| id | doaj.art-75c2b63899834916a88cf490263fb5b2 |
| institution | Directory Open Access Journal |
| issn | 2079-4991 |
| language | English |
| last_indexed | 2024-03-11T03:00:43Z |
| publishDate | 2023-05-01 |
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| series | Nanomaterials |
| spelling | doaj.art-75c2b63899834916a88cf490263fb5b22023-11-18T08:18:35ZengMDPI AGNanomaterials2079-49912023-05-011311171810.3390/nano13111718Effect of Acidic Strength of Surface Ligands on the Carrier Relaxation Dynamics of Hybrid Perovskite NanocrystalsSudhakar Narra0Po-Sen Liao1Sumit S. Bhosale2Eric Wei-Guang Diau3Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu 300093, TaiwanDepartment of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu 300093, TaiwanDepartment of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu 300093, TaiwanDepartment of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu 300093, TaiwanPerovskite 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 Cs<sub>x</sub>FA<sub>(1−x)</sub>PbBr<sub>y</sub>I<sub>(3−y)</sub> 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.https://www.mdpi.com/2079-4991/13/11/1718perovskite nanocrystalsred emissionsurface ligandsdefect passivationcharge extractionexciton |
| spellingShingle | Sudhakar Narra Po-Sen Liao Sumit S. Bhosale Eric Wei-Guang Diau Effect of Acidic Strength of Surface Ligands on the Carrier Relaxation Dynamics of Hybrid Perovskite Nanocrystals Nanomaterials perovskite nanocrystals red emission surface ligands defect passivation charge extraction exciton |
| title | Effect of Acidic Strength of Surface Ligands on the Carrier Relaxation Dynamics of Hybrid Perovskite Nanocrystals |
| title_full | Effect of Acidic Strength of Surface Ligands on the Carrier Relaxation Dynamics of Hybrid Perovskite Nanocrystals |
| title_fullStr | Effect of Acidic Strength of Surface Ligands on the Carrier Relaxation Dynamics of Hybrid Perovskite Nanocrystals |
| title_full_unstemmed | Effect of Acidic Strength of Surface Ligands on the Carrier Relaxation Dynamics of Hybrid Perovskite Nanocrystals |
| title_short | Effect of Acidic Strength of Surface Ligands on the Carrier Relaxation Dynamics of Hybrid Perovskite Nanocrystals |
| title_sort | effect of acidic strength of surface ligands on the carrier relaxation dynamics of hybrid perovskite nanocrystals |
| topic | perovskite nanocrystals red emission surface ligands defect passivation charge extraction exciton |
| url | https://www.mdpi.com/2079-4991/13/11/1718 |
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