Band offset at TiO<sub>2</sub>/MDMO PPV and TiO<sub>2</sub>/PEDOT PSS interfaces studied using photoelectron spectroscopy

Ajimsha, R. S.; Joshi, M. P.; Mohan, S. Raj; Das, Amit K.; Misra, Pankaj; Kukreja, L. M.; Phase, D. M.

doi:10.1039/c5ra21227h

Cited by 15 publications

(9 citation statements)

References 44 publications

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“…The estimated VBM values of GaN NRs and the composite polymer were found to be 2.7 and 1.4 eV, respectively. Using the VBM and core-level data, we have calculated the valence band offset (VBO) for the Ppy-PEDOT:PSS/GaN NRs hybrid structure based on the standard equation proposed by Kraut’s et al , …”

Section: Resultsmentioning

confidence: 95%

Ag Nanowire-Plasmonic-Assisted Charge Separation in Hybrid Heterojunctions of Ppy-PEDOT:PSS/GaN Nanorods for Enhanced UV Photodetection

Pasupuleti

Reddeppa

Park

et al. 2020

ACS Appl. Mater. Interfaces

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The surface states, poor carrier life, and other native defects in GaN nanorods (NRs) limit their utilization in high-speed and large-gain ultraviolet (UV) photodetection applications. Making a hybrid structure is one of the finest strategies to overcome such impediments. In this work, a polypyrrole (Ppy)-poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/GaN NRs hybrid structure is introduced for self-powered UV photodetection applications. This hybrid structure yields high photodetection performance, while pristine GaN NRs showed negligible photodetection properties. The ability of the photodetector is further boosted by functionalizing the hybrid structure with Ag nanowires (NWs). The Ag NWsfunctionalized hybrid structure exhibited a responsivity of 3.1 × 10 3 (A/W), detectivity of 3.19 × 10 14 Jones, and external quantum efficiency of 1.0 6 × 10 6 (%) under a UV illumination of λ = 382 nm. This high photoresponse is due to the huge photon absorption rising from the localized surface plasmonic effect of a Ag NWs network. Also, the Ag NWs significantly improved the rising and falling times, which were noted to be 0.20 and 0.21 s, respectively. The model band diagram was proposed with the assistance of X-ray photoelectron spectroscopy to explore the origin of the superior performance of the Ag NWs-decorated Ppy-PEDOT:PSS/GaN NRs photodetector. The proposed hybrid structure seems to be a promising candidate for the development of high-performance UV photodetectors.

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Section: Resultsmentioning

confidence: 95%

Ag Nanowire-Plasmonic-Assisted Charge Separation in Hybrid Heterojunctions of Ppy-PEDOT:PSS/GaN Nanorods for Enhanced UV Photodetection

Pasupuleti

Reddeppa

Park

et al. 2020

ACS Appl. Mater. Interfaces

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“…Polypyrrole (Ppy, E g ≈3.1 eV) is a typical p‐type conductive polymer, which has attracted significant research attention in optoelectronics owing to its high electrical conductivity and excellent optical properties. [ 6 ] Thus, the fascinating integration of Ppy polymers on GaN nanorods establishes an interface junction and imparts the synergetic charge transfer between the junction interfaces, [ 7 ] which could effectively influence the photoresponse properties under UV light illumination.…”

Section: Figurementioning

confidence: 99%

“…[ 12 ] Moreover, the peak shift in the Ga 3d spectra of pristine GaN NRs and the Ppy/GaN NRs samples in Figure 1f is an evidential proof for the existence of charge interaction in‐between the hybrid interface. [ 7,13 ]…”

Section: Figurementioning

confidence: 99%

“…[12] Moreover, the peak shift in the Ga 3d spectra of pristine GaN NRs and the Ppy/GaN NRs samples in Figure 1f is an evidential proof for the existence of charge interaction in-between the hybrid interface. [7,13] Furthermore, the charge transfer mechanism between the hybrid interfaces was evaluated using XPS band offset values shown in Figure 2a-d. The calculated conduction band offset (CBO) and valence band offset (VBO) values were found to be ΔE c ¼ 0.95 AE 0.1 eV and ΔE v ¼ 1.26 AE 0.1 eV by substituting the obtained values from the XPS analysis using the standard equation reported elsewhere.…”

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confidence: 99%

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Efficient Charge Separation in Polypyrrole/GaN‐Nanorod‐Based Hybrid Heterojunctions for High‐Performance Self‐Powered UV Photodetection

Pasupuleti

Reddeppa

Park

et al. 2021

Physica Rapid Research Ltrs

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The ozonosphere is infiltrated by UV‐A rays (λ = 320–400 nm) that reach the Earth's atmosphere, posing serious health problems such as premature aging and skin cancer. Owing to the importance of UV‐A ray detection, highly detective, novel, and high‐speed UV‐A photodetectors have recently attracted considerable attention. The integration of organic and inorganic hybrid structures yields highly attractive optoelectronic properties that make them attractive candidates for high‐performance self‐powered UV‐A photodetectors. Herein, the integration of conductive polypyrrole (Ppy) and GaN nanorods for high‐performance self‐powered UV‐A photodetectors is demonstrated. The device exhibits superior photoresponse properties such as detectivity, responsivity, and external quantum efficiency values as 5.0 × 1012 Jones, 102 A W−1, and 29.8 × 103%, respectively, at a power density of 1.32 mW cm−2 (λ = 382 nm) and zero bias, which are relatively higher than those of pristine GaN nanorods. Furthermore, the device exhibits good stability and reproducibility with fast rising (350 ms) and falling (410 ms) times. The high photoresponse is attributed to the large built‐in potential formed at the interface junction of the Ppy and the GaN nanorods. Furthermore, the mechanism behind the high photoresponse is investigated using an X‐ray photoelectron spectroscopy (XPS) analysis and energy band theory.

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“…2,9 Metal oxides such as TiO 2 are suitable acceptors; however, photovoltaic devices comprising oxide nanoparticles and polymers have historically shown low efficiencies. 10 Studies have shown that energy alignment at the interface is an important factor, 10−14 and by using small molecular surface modifiers such as benzoic acids, the interfacial dipole can induce band edge shifts that can facilitate charge carrier generation. 15 A recent study suggests that a key reason for the limited photocurrent in metal oxide−polymeric BHJ photovoltaic devices may be due to the downward band bending (decreasing energy moving away from the interface) in the polymer.…”

Section: ■ Introductionmentioning

confidence: 99%

Effects of Surface Passivation on Trap States, Band Bending, and Photoinduced Charge Transfer in P3HT/TiO₂ Hybrid Inverse Opals

2018

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We investigate the effect of a common TiO2 passivation reagent, TiCl4, on the photoinduced charge transfer of poly(3-hexylthiophene) (P3HT) to TiO2 in the inverse opal structure. Treating the inorganic oxide framework with TiCl4 leads to an increase in the size of the TiO2 nanoparticles, a thickening of the inverse opal framework, and a decrease in the trap-state photoluminescence. These changes lead to different energy alignments at the interface. In comparison to the unpassivated P3HT/TiO2 inverse opal, we measured a larger polaron yield, by as high as ninefold, and significantly shorter and more uniformly distributed polaron lifetimes in TiCl4-treated samples. We show that downward band bending in the polymer can be circumvented by tuning the trap states on the metal oxide using TiCl4, thereby eliminating the energetic barrier for photoelectron injection from the polymer to the metal oxide. The findings suggest a way to overcome a potential factor that has plagued the performance of metal oxide–polymer hybrid photovoltaics.

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Band offset at TiO₂/MDMO PPV and TiO₂/PEDOT PSS interfaces studied using photoelectron spectroscopy

Abstract: We report band alignment and band offset studies across the interfaces of hetero-structures of TiO2 with MDMO PPV and PEDOT PSS using photoelectron spectroscopy.

Cited by 15 publications

References 44 publications

Ag Nanowire-Plasmonic-Assisted Charge Separation in Hybrid Heterojunctions of Ppy-PEDOT:PSS/GaN Nanorods for Enhanced UV Photodetection

Ag Nanowire-Plasmonic-Assisted Charge Separation in Hybrid Heterojunctions of Ppy-PEDOT:PSS/GaN Nanorods for Enhanced UV Photodetection

Efficient Charge Separation in Polypyrrole/GaN‐Nanorod‐Based Hybrid Heterojunctions for High‐Performance Self‐Powered UV Photodetection

Effects of Surface Passivation on Trap States, Band Bending, and Photoinduced Charge Transfer in P3HT/TiO₂ Hybrid Inverse Opals

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Band offset at TiO2/MDMO PPV and TiO2/PEDOT PSS interfaces studied using photoelectron spectroscopy

Abstract: We report band alignment and band offset studies across the interfaces of hetero-structures of TiO2 with MDMO PPV and PEDOT PSS using photoelectron spectroscopy.

Cited by 15 publications

References 44 publications

Ag Nanowire-Plasmonic-Assisted Charge Separation in Hybrid Heterojunctions of Ppy-PEDOT:PSS/GaN Nanorods for Enhanced UV Photodetection

Ag Nanowire-Plasmonic-Assisted Charge Separation in Hybrid Heterojunctions of Ppy-PEDOT:PSS/GaN Nanorods for Enhanced UV Photodetection

Efficient Charge Separation in Polypyrrole/GaN‐Nanorod‐Based Hybrid Heterojunctions for High‐Performance Self‐Powered UV Photodetection

Effects of Surface Passivation on Trap States, Band Bending, and Photoinduced Charge Transfer in P3HT/TiO2 Hybrid Inverse Opals

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Band offset at TiO₂/MDMO PPV and TiO₂/PEDOT PSS interfaces studied using photoelectron spectroscopy

Effects of Surface Passivation on Trap States, Band Bending, and Photoinduced Charge Transfer in P3HT/TiO₂ Hybrid Inverse Opals