Effect of annealing temperature on nano-crystalline TiO2 for solar cell applications

• Published in: Physica. E, Low-dimensional systems & nanostructures Low-dimensional systems & nanostructures, 2019-02, Vol.106, p.127-132
• Main Authors: Malevu, T.D., Mwankemwa, B.S., Motloung, S.V., Tshabalala, K.G., Ocaya, R.O.
• Format: Article
• Language: English
• Subjects: Anatase TiO2 nanocrystals; Annealing temperature; Hydrothermal crystal growth; Phase transformation
• ISSN: 1386-9477; 1873-1759
• DOI: 10.1016/j.physe.2018.10.028

This study investigates the effect of annealing temperature (AT) on structure, morphology and optical properties of hydrothermally synthesized TiO2 nanocrystals. Selected-Area Diffraction (SAED) confirmed high quality monocrystals. XRD and Raman spectroscopy indicate only anatase and rutile phases. At high temperature, the (101) and (001) are preferred. PL emission peaks appear at 407, 416 and 493 nm, which can be attributed to photo-excited electron-hole pairs, band-edge excitons and oxygen vacancy defects, respectively. UV–Vis spectroscopy indicates that AT over the 200–600 °C temperature range causes the band gap to decrease from 3.08 eV to 2.73 eV. Hydrothermal synthesis followed by annealing at 600 °C is found to be a good route for high-purity, nanocrystalline anatase-phase TiO2 with the preferred {001} orientation that is thought to enhance solar cell performance. •We have successfully synthesized TiO2 with {001} facet.•We have investigated the effect of annealing temperature on TiO2.•We use standard techniques of XRD, SEM, TEM, PL, UV–Vis Raman spectroscopy to identify products.•Research promises to further enhance the performance of solar cell devices.