Electronic structure and optoelectronic performance of a nanostructured copper(ii) pyranoquinoline complex: DFT insights for temperature-sensing and photodetection applications

Multifunctional organic-inorganic materials are promising candidates for next-generation optoelectronic devices. This study reports the design, characterization, and device application of a copper-based pyranoquinoline complex, Cu(HMDPQ), with enhanced optoelectronic performance. Structural analysis confirmed a square-planar geometry with bidentate oxygen coordination. Density functional theory (DFT) calculations using the 6-311G(d,p) basis set supported the experimental findings, revealing an energy gap of 2.86 eV and a pronounced nonlinear optical (NLO) response attributed to efficient intramolecular charge transfer. Thin films showed uniform morphology, an average grain size of 80.3 nm, and low surface roughness (∼8.5 nm), favoring charge transport. Optical studies revealed dual direct band gaps (1.81 and 1.93 eV), strong blue emission, and lower-energy transitions from metal-ligand interactions. A metal/organic/semiconductor heterojunction exhibited rectifying behavior, low dark current (∼1.6 × 10^-8 A cm^-2), a barrier height of ∼1.05 eV, responsivity of 3.7 × 10^-2 A W^-1, and detectivity of 5.2 × 10¹¹ Jones, demonstrating potential for photodetector and temperature-sensing applications.