Low-Temperature Solution Combustion-Synthesized CuSNanoparticulated Functional Thin Films: Structural and Optoelectronic Characterization Studies

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).