Donal Bradley

Abstract:

Perovskite nanocrystals (NCs) demonstrate exceptional potential as emitters to address Rec. 2020 standards for wide color gamut displays. However, the pure-red-targeted CsPbI3 NCs generally suffer from imprecise synthetic control over emission wavelength and from structural instabilities that significantly diminish performance. We report a novel halogen engineering framework that addresses the otherwise unfavorable wavelength-efficiency-stability nexus. Our approach leverages surface I-···I2 interactions to simultaneously unlock exceptional optical characteristics and the elusive structural robustness needed for application. It achieves: (i) controlled quantum-confinement-tuned emission wavelength, (ii) near-unity photoluminescence (PL) quantum yield through iodide vacancy defect management, and (iii) excellent environmental stability, even under harsh (85°C/85%) temperature and humidity conditions, through lattice-distortion suppression. Rec. 2020 compliant, 638 nm peak light-emitting diodes (LEDs) are then demonstrated with Commission Internationale de l'Éclairage coordinates (X, Y) = (0.703, 0.297), 22% external quantum efficiency, luminance ≥ 11,000 cd m-2, and long lifetime, establishing a materials-by-design paradigm for advancing next-generation perovskite display technologies.

Abstract:

In this paper, we present a one-step low-temperature solution combustion synthesis (SCS) of CuS nanoparticulated functional films processed via a simple blade-coating technique. This SCS route uses thiourea as a fuel and sulfur source, combined with copper(II) nitrate as an oxidant and a cupric ion source in an aprotic solvent such as non-toxic DMSO. It is hereby shown that the proposed SCS process formed a stable and completely dissolved molecular ink of thiourea and copper ion complexes, crucial for obtaining the pure crystalline phase of CuS nanoparticles (NPs). The CuS was formed by calcination at a low temperature of 200 °C during a brief annealing time of 20 min, to promote the synthesis of ~10 nm CuS NPs. The obtained CuS NPs were thoroughly analyzed in terms of structure and optoelectronic properties using various analytic and spectroscopic techniques, including TGA, XRD, FE-SEM, EDS, AFM, and four-point probe electrical resistivity measurements. The functionality of the prepared CuS nanoparticulated interlayers was evaluated by incorporating them as a hole injection layer (HIL) in Super Yellow (SY) organic light-emitting diodes (OLEDs).