Simultaneous Effect of Ultraviolet Radiation and Surface Modification on the Work Function and Hole Injection Properties of ZnO Thin Films

Raoufi, Meysam; Hörmann, Ulrich; Ligorio, Giovanni; Hildebrandt, Jana; Pätzel, Michael; Schultz, Thorsten; Perdigon, Lorena; Koch, Norbert; List‐Kratochvil, Emil J. W.; Hecht, Stefan; Neher, Dieter

doi:10.1002/pssa.201900876

Cited by 7 publications

(12 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The low UV absorption hinders the first step that leads to changes in the property of the ETLs. Moreover, in contrast to the repeatable generation and degeneration of photoinduced shunting caused by oxygen desorption and reabsorption cycles in ZnO, the surface electronic properties of SnO 2 were found distinctively stable with an accumulation layer due to surface water absorbate, showing indifference to external ambient (oxygen or vacuum) and illumination conditions. ,,, Such a feature prevents dramatic changes in the charge transport properties at the organic/metal oxide interface.…”

Section: Resultsmentioning

confidence: 90%

Understanding and Countering Illumination-Sensitive Dark Current: Toward Organic Photodetectors with Reliable High Detectivity

et al. 2021

View full text Add to dashboard Cite

Continuously enhanced photoresponsivity and suppressed dark/noise current combinatorially lead to the recent development of high-detectivity organic photodetectors with broadband sensing competence. Despite the achievements, reliable photosensing enabled by organic photodetectors (OPDs) still faces challenges. Herein, we call for heed over a universal phenomenon of detrimental sensitivity of dark current to illumination history in high-performance inverted OPDs. The phenomenon, unfavorable to the attainment of high sensitivity and consistent figures-of-merit, is shown to arise from exposure of the commonly used electron transport layer in OPDs to high-energy photons and its consequent loss of charge selectivity via systematic studies. To solve this universal problem, “double” layer tin oxide as an alternative electron transport layer is demonstrated, which not only eliminates the inconsistency between the initial and after-illumination dark current characteristics but also preserves the low magnitude of dark current, good external quantum efficiency, and rapid transient response.

show abstract

Section: Resultsmentioning

confidence: 90%

Understanding and Countering Illumination-Sensitive Dark Current: Toward Organic Photodetectors with Reliable High Detectivity

et al. 2021

View full text Add to dashboard Cite

show abstract

“…We carried out Kelvin probe measurements to investigate the work function shifts of ZnO, SnO 2 , and InAs CQD solids under ambient air with and without UV light exposure (Figure 2c). [ 51,52 ] The initial work function of ZnO was obtained using Kelvin probe measurements, with a value of 4.77 eV. When ZnO was illuminated with UV light, the work function of ZnO significantly decreased to 4.45 eV because of the charge redistribution resulting from the desorption of the chemisorbed oxygen ions on the ZnO surfaces.…”

Section: Resultsmentioning

confidence: 99%

“…Chemisorbed oxygen ions (i.e., O 2 − ) on the oxygen-deficient surface of metal oxides can be desorbed via the recombination of the photo-generated holes with the electrons of oxygen ions 2c). [51,52] The initial work function of ZnO was obtained using Kelvin probe measurements, with a value of 4.77 eV. When ZnO was illuminated with UV light, the work function of ZnO significantly decreased to 4.45 eV because of the charge redistribution resulting from the desorption of the chemisorbed oxygen ions on the ZnO surfaces.…”

Section: Air-and Photo-stabilities Of the Pm6:y6 Bhj Absorbermentioning

confidence: 99%

“…When ZnO was illuminated with UV light, the work function of ZnO significantly decreased to 4.45 eV because of the charge redistribution resulting from the desorption of the chemisorbed oxygen ions on the ZnO surfaces. [52,53] After turning off the UV light, the work function began to increase over time, possibly due to the re-absorption of oxygen ions on the ZnO surfaces under ambient air. In the case of less photocatalytic SnO 2 , the overall change in work function was much less than that of ZnO but still occurred.…”

Section: Air-and Photo-stabilities Of the Pm6:y6 Bhj Absorbermentioning

confidence: 99%

See 1 more Smart Citation

Charge‐Selective, Narrow‐Gap Indium Arsenide Quantum Dot Layer for Highly Stable and Efficient Organic Photovoltaics

Park

Bae

Kim

et al. 2022

Advanced Energy Materials

View full text Add to dashboard Cite

The past decade has seen a dramatic surge in the power conversion efficiency (PCE) of next‐generation solution‐processed thin‐film solar cells rapidly closing the gap in PCE of commercially‐available photovoltaic (PV) cells. Yet the operational stability of such new PVs leaves a lot to be desired. Specifically, chemical reaction with absorbers via high‐energy photons transmitted through the typically‐adapted metal oxide electron transporting layers (ETLs), and photocatalytic degradation at interfaces are considered detrimental to the device performance. Herein, the authors introduce a device architecture using the narrow‐gap, Indium Arsenide colloidal quantum dots (CQDs) with discrete electronic states as an ETL in high‐efficiency solution‐processed PVs. High‐performing PM6:Y6 organic PVs (OPVs) achieve a PCE of 15.1%. More importantly, as the operating stability of the device is significantly improved, retaining above 80% of the original PCE over 1000 min under continuous illumination, a Newport‐certified PCE of 13.1% is reported for nonencapsulated OPVs measured under ambient air. Based on operando studies as well as optical simulations, it suggested that the InAs CQD ETLs with discrete energy states effectively cut‐off high‐energy photons while selectively collecting electrons from the absorber. The findings of this works enable high‐efficiency solution‐processed PVs with enhanced durability under operating conditions.

show abstract

“…The adsorbed oxygen can also create a potential barrier of upward band bending by a depletion region along the ZnO surface, causing a high work function (WF) [ 24 , 25 , 26 ]. After UV irradiation, the adsorbed oxygen in the ZnO is released, which leads to less band bending and lower WF [ 27 ].…”

Section: Resultsmentioning

confidence: 99%

Effects of UV Irradiation and Storage on the Performance of Inverted Red Quantum-Dot Light-Emitting Diodes

Luo

Wang

et al. 2021

Nanomaterials

View full text Add to dashboard Cite

We report the effects of ultraviolet (UV) irradiation and storage on the performance of ZnO-based inverted quantum-dot light-emitting diodes (QLEDs). The effects of UV irradiation on the electrical properties of ZnO nanoparticles (NPs) were investigated. We demonstrate that the charge balance was enhanced by improving the electron injection. The maximum external quantum efficiency (EQE) and power efficiency (PE) of QLEDs were increased by 26% and 143% after UV irradiation for 15 min. In addition, we investigated the storage stabilities of the inverted QLEDs. During the storage period, the electron current from ZnO gradually decreased, causing a reduction in the device current. However, the QLEDs demonstrated improvements in maximum EQE by 20.7% after two days of storage. Our analysis indicates that the suppression of exciton quenching at the interface of ZnO and quantum dots (QDs) during the storage period could result in the enhancement of EQE. This study provides a comprehension of the generally neglected factors, which could be conducive to the realization of high-efficiency and highly storage-stable practical applications.

show abstract

Simultaneous Effect of Ultraviolet Radiation and Surface Modification on the Work Function and Hole Injection Properties of ZnO Thin Films

Cited by 7 publications

References 29 publications

Understanding and Countering Illumination-Sensitive Dark Current: Toward Organic Photodetectors with Reliable High Detectivity

Understanding and Countering Illumination-Sensitive Dark Current: Toward Organic Photodetectors with Reliable High Detectivity

Charge‐Selective, Narrow‐Gap Indium Arsenide Quantum Dot Layer for Highly Stable and Efficient Organic Photovoltaics

Effects of UV Irradiation and Storage on the Performance of Inverted Red Quantum-Dot Light-Emitting Diodes

Contact Info

Product

Resources

About