Enhanced structural and optical performance of the novel 3-[(5-amino-1-phenyl-1H-pyrazol-4-yl)carbonyl]-1-ethyl-4-hydroxyquinolin-2(1H)-one heterojunction: experimental and DFT modeling

This study successfully and cost-effectively synthesized a novel compound, 3-[(5-amino-1-phenyl-1H-pyrazol-4-yl)carbonyl]-1-ethyl-4-hydroxyquinolin-2(1H)-one (APPQ, 4), which displayed significant potential for various applications and yielded promising outcomes. Theoretical electronic absorption spectra in different media were acquired using the Coulomb-attenuating approach (CAM-B3LYP) and the Corrected Linear Response Polarizable Continuum Model (CLR) PCM. Employing CAM-B3LYP with the 6-311 +  + G(d,p) level of DFT proved to be more accurate than alternative quantum chemical calculation methods, aligning well with the experimental data. Additionally, the CAM-B3LYP method using polarized split-valence 6-311 +  + G(d,p) basis sets and CLR PCM in various solvents exhibited good agreement with the observed spectra. The high stability of APPQ, validated by the computed total energy and thermodynamic parameters at the same calculation level, surpassed that of anticipated structure 3. The theoretically calculated chemical shift values (¹H and ¹³C) and vibrational wavenumbers were strongly correlated with the experimental data. The APPQ thin films demonstrated a band gap energy of 2.3 eV through distinctive absorption edge measurement. Photoluminescence spectra exhibited characteristic emission peaks at approximately 580 nm. Current–voltage measurements on n-Si heterojunction devices with APPQ thin films revealed typical diode behavior. These APPQ-based devices showed attractive photovoltaic properties, including an open-circuit voltage of 0.62 V, a short-circuit current of 5.1 × 10^–4 A/cm², and a maximum output power of 0.247 mW/cm². Overall, the investigated heterojunctions display appealing photophysical characteristics, encouraging advancements in photovoltaics.