Optimizing solar cell performance: Synthesis, structural, and optical analysis of novel quinolinopyranopyridopyrimidine (QPPP)

In this study, we report the synthesis and characterization of quinolinopyranopyrido-pyrimidine (QPPP, 3) through the reaction of 6-ethyl-4,5-dioxo-5,6-dihydro-4H-pyrano[3,2-c]quinoline-3-carbonitrile (1) with thiobarbituric acid (2). Computational studies employing density functional theory (DFT) at the B3LYP/6-311++G(d,p) level were conducted to investigate the stable geometries, molecular electrostatic potential (MEP) surfaces, non-linear optical (NLO) properties, and frontier molecular orbital (FMO) analysis. Theoretical chemical shift values (¹H and ¹³C) and vibrational wavenumber values showed a good correlation with experimental data. An in silico ADMET analysis indicated favorable oral drug-like properties for the studied compounds. Scanning electron microscopy was used to analyze the topography of the QPPP structure, revealing high absorption characteristics with two distinct values of 3.42 and 4.12 eV and a directly allowed energy gap of 3.03 eV. QPPP films exhibited remarkable photoluminescence at 514.18, 595.08, and 710.8 nm, indicating their suitability for optoelectronic applications. Furthermore, the investigation of the J-V characteristics of QPPP film-based devices under various illuminations demonstrated a distinct response to incident light, suggesting potential utility in organic solar cells. The heterojunctions of Au/QPPP/n-Si/In showed a suitable solar cell feature in the dark and under illuminations ranging from 20 mW/cm² to 80 mW/cm². Under illumination, the short-circuit current and open-circuit voltage increased from 0.86 mA to 5.49 mA and from 0.178 V to 0.487 V, respectively. The QPPP-based heterojunction solar cells exhibited noticeable enhancements in both fill factor and solar cell efficiency, reaching approximately 0.36 and 5.6 % under 80 mW/cm², respectively. These findings underscore the potential of QPPP-based materials for use in efficient organic solar cells.