High Hall Mobility P-type Cu₂SnS₃-Ga₂O₃ with a High Work Function

A new transparent p-type oxide semiconductor (POS) is reported, Cu₂SnS₃-Ga₂O₃, having high Hall mobility of 36.22 cm² V⁻¹s⁻¹, and high work function of 5.17 eV. The existence of Cu₂SnS₃ and Ga₂O₃ phases in the film is confirmed by X-ray photoelectron spectroscopy results and the Cu₂SnS₃ shows polycrystalline structure according to Raman spectrum and X-ray diffraction analysis. The transparent Cu₂SnS₃-Ga₂O₃ exhibits the carrier concentration of 5.86 × 10¹⁶ cm⁻³, and electrical resistivity of 1.94 Ω·cm. The transparent POS is applied to green quantum light-emitting diodes (QLEDs) as a hole injection layer (HIL) because of its high work function. The QLED exhibits the maximum current efficiency of 51.72 cd A⁻¹, power efficiency of 31.97 lm W⁻¹, and external quantum efficiency (EQE) of 14.93%, which are much higher than the QLED using polyethylene dioxythophene:poly(styrenesulfonate) HIL exhibiting current efficiency of 42.66 cd A⁻¹, power efficiency of 20.33 lm W⁻¹, and EQE of 12.36%. The Cu₂SnS₃-Ga₂O₃ developed in this work can be widely used as a transparent and conductive p-type oxide for thin-film devices.