Abstract

ABSTRACT (ta-C) films coated through the filtered cathodic vacuum arc (FCVA) process as a hole transport layer (HTL) for perovskite solar cells (PSCs) and quantum dot light-emitting diodes (QDLEDs). The p-type ta-C film has several remarkable features, including ease of fabrication without the need for thermal annealing, reasonable electrical conductivity, optical transmittance, and a high work function. X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy examinations show that the electrical properties (sp3/sp2 hybridized bond) and work function of the ta-C HTL are appropriate for PSCs and QDLEDs. In addition, in order to correlate the performance of the devices, the optical, surface morphological, and structural properties of the FCVA-grown ta-C films with different thicknesses (5 ~ 20 nm) deposited on the ITO anode are investigated in detail. The optimized ta-C film with a thickness of 5 nm deposited on the ITO anode had a sheet resistance of 10.33 Ω−2, a resistivity of 1.34 × 10−4 Ω cm, and an optical transmittance of 88.97%. Compared to the reference PSC with p-NiO HTL, the PSC with 5 nm thick ta-C HTL yielded a higher power conversion efficiency (PCE, 10.53%) due to its improved fill factor. Further, the performance of QDLEDs with 5 nm thick ta-C hole injection layers (HIL) showed better than the performance of QDLEDs with different ta-C thicknesses. It is concluded that ta-C films have the potential to serve as HTL and HIL in next-generation PSCs and QDLEDs.

Highlights

  • In recent years, organic-inorganic metal halide perovskite solar cells (PSCs) and quantum dot light emission diodes (QDLEDs) have attracted substantial research interest for use in next-generation photovoltaics and flat panel displays because of the high solarto-electric power conversion efficiency (PCE) of PSCs and interesting property characteristic, such as good color purity with narrow full-width at half maximum (FWHM) emission of QDLEDs [1–13]

  • The results suggest that the combination of diamond-like mechanical properties and tunable electrical and optical properties of Tetrahedral amorphous carbon (ta-C) film makes it applicable to hole transport or injection layers for PSCs and QDLEDs, respectively

  • We demonstrated the usage of ta-C/ITO anodes fabricated through the filtered cathodic vacuum arc (FCVA) process as a hole transport or injection for PSCs and QDLEDs

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Summary

Introduction

Organic-inorganic metal halide perovskite solar cells (PSCs) and quantum dot light emission diodes (QDLEDs) have attracted substantial research interest for use in next-generation photovoltaics and flat panel displays because of the high solarto-electric power conversion efficiency (PCE) of PSCs and interesting property characteristic, such as good color purity with narrow full-width at half maximum (FWHM) emission of QDLEDs [1–13]. High-efficiency PSCs and QDLEDs have generally adopted organic-inorganic composite multilayer structures, in which the CTLs consist of organic polymers and inorganic metal oxide – as a hole transport layer (HTL) in the case of PSCs or as a hole injection layer (HIL) in the case of QDLEDs – exhibiting outstanding device performance [30–37]. The limited hole transport or injection efficiency is one of the large obstacles to further improvements in the performances of PSCs and QDLEDs. For instance, the inherent acidity of PEDOT:PSS can damage indium tin oxide (ITO) anodes by dissolving indium species, and the hygroscopic nature accelerates the diffusion of indium, which both significantly affect the device stability [38– 40]. Solutionbased metal-oxide HTL has critical problems with large area coating and ensuring exact control of the thickness and composition As another replacement of PEDOT: PSS, carbon-based materials (tetrahedral amorphous carbon, graphene, fullerene, and carbon nanotubes) have been investigated. Based on the performances of PSCs and QDLEDs with ta-C HTL, we propose ta-C film as a promising HTL to substitute PEDOT:PSS in PSCs and QDLEDs

Fabrication of ITO electrodes on glass substrates by magnetron sputtering
Coating of ta-C layer by single-cathode FCVA
Fabrication and evaluation of PSCs and QDLEDs
Results and discussion
Conclusions
Full Text
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