Improvement of Dye-Sensitized Solar Cells (DSSCs) performance using Crude Brazilein Extract from Sappanwood (Caesalpinia Sappan L.) with the incorporation of ZnO nanoparticles

•The color of the crude extract of Sappanwood was changed from yellow-orange to deep crimson when it reacted with ZnO-NP.•Addition of ZnO-NP caused brazilin to oxidize and form brazilein.•ZnO-NP and brazilein interact through a coordination covalent bond•The addition of ZnO-NP extends the CBE's band absorption edge and enhances its capability to absorb light.•The immersion time and addition of ZnO-NP increase both the short-circuit current density (Jsc) and the open-circuit voltage (Voc) value of the DSSCs cell. We synthesized a crude extract of Sappanwood (Caesalpinia sappan L.) and incorporated the ZnO nanoparticles (ZnO-NP) as the natural light-harvesting material (dye). The maceration method was used to extract crude brazilein from Sappanwood. The physical and chemical properties of the crude brazilein extract (CBE) and CBE-incorporated ZnO-NP were investigated using a UV-Vis spectrometer, XRD, FTIR, and LSV. The performance of the natural dye in the DSSC was investigated concerning the immersion time of 6, 12, 18, and 24 hours, using current-voltage measurement. ZnO-NP addition led to an increase in the concentration of the aromatic functional group. The UV-Vis measurement of CBE showed the most intense peak at 490 nm. A red shift was observed in the absorbance spectrum of CBE-incorporated ZnO-NP. The reduction current was observed for all samples where its value decreased as the immersion time was longer. The I-V measurements showed that immersion time affected both current density (Jsc) and open-circuit voltage (Voc), as the longer immersion time resulted in higher Jsc and Voc leading to higher overall conversion efficiency (η), this applied for both CBE and CBE-incorporated ZnO-NP. The utilization of CBE-incorporated ZnO-NP highly improved the photovoltaic properties of the DSSC cells for all immersion time, specifically for 24 hours, the Jsc, Voc, and η values increased as much as 135.7%, 60.4%, and 550% respectively, reaching the highest efficiency of 2.6%. The above results confirmed that Sappanwood can be utilized as an efficient, low-cost cost, and environmentally friendly source of natural dye for DSSC application. Future development will be directed toward purifying the extract and elaboration of other metals as stabilizing agents. [Display omitted]