Engineering ZnO photoanodes for enhanced DSSC performance via Bi-functionalization

Co-sensitization of photoanodes represents a cutting-edge strategy for enhancing the efficiency of photovoltaic cells. This study explores the potential of ZnO thin films and investigates natural dyes extracted from Clitoria Ternatea leaves (D1) and flowers (D2) as individual and combined sensitizers for Natural dye-sensitized solar cells (NDSSCs). UV-VIS and FTIR spectroscopies confirm the presence of Chlorophyll-a in D1 and Anthocyanin in D2. Photoelectrochemical analysis reveal that, ZnO co-sensitized NDSSCs achieve superior performance, with a V_OC of 209 mV, I_SC of 2.3 mA, energy conversion efficiency (η) of 3.4 %, and a fill factor of 35.4 % which surpass those obtained from NDSSCs using single-dye sensitizers. ZnO thin films were further analyzed using UV-VIS spectroscopy, PXRD, FESEM, and EDAX. The absorption spectrum indicates a band gap (E_g) of 3.1 eV. PXRD data confirm hexagonal wurtzite phase (space group P63mc), FESEM reveals a distinctive flower-like morphology and EDAX analysis confirms a Zn-to-O ratio of 1:1.