Influence of oxygen ions irradiation on the optical properties of photoanodes for dye sensitized solar cell

¹Material Science Lab., Department of Physics, Chaudhary Devi Lal University, Sirsa, Haryana 125055, India

²Laser Laboratory, Department of Applied Physics, Guru Jambheshwar University of Science &Technology, Hisar 125001, Haryana, India

³Inter-University Accelerator Centre, New Delhi 110067, India

Adv. Mater. Lett., 2017, 8 (4), pp 565-571

DOI: 10.5185/amlett.2017.6518

Publication Date (Web): Mar 15, 2017

Copyright © IAAM-VBRI Press

E-mail: amrik23kuk@gmail.com

Abstract

Indium Tin Oxide (ITO) coated glass acts as a substrate for photoanode of Dye Sensitized Solar Cells (DSSCs). The ITO substrate was irradiated by oxygen ion with different fluence (1x10¹¹ and 1x10¹² ions/cm²) at 100 MeV energy. The TiO₂ films were also subjected with same ion irradiation at 100 MeV of energy with fluence of 1x10¹¹ ions/cm² and 5x10¹² ions/cm². At 100 MeV energy of O⁷⁺ ion the electronic and nuclear energy loss for TiO₂ film have been measured 7.38x10^-1 KeV/nm and 3.8x10^-4 KeV/nm respectively.  However, the electronic and nuclear energy loss of ion irradiation for ITO substrate were 7.4x10^-1 KeV/nm and 4.06x10^-4 KeV/nm respectively. Similarly longitudinal/ lateral straggling of ITO and TiO₂ have been found 3.87 μm/2.50 µm and 3.62 µm/1.14 μm respectively. Further, the structural and optical properties of these samples were monitored by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-visible spectroscopy. It was found that oxygen ion (O⁷⁺) irradiation of ITO film has slightly changed the crystallinity and transmission decreases. Furthermore, the particle size of TiO₂ thin film has been obtained 80 nm corresponding to (101) plane of XRD pattern. In the case of ITO thin film the crystallite size and band gap changes from 62.35 nm to 53.89 nm and 3.993 eV to 3.971 eV at 1x10¹² ions/cm² respectively. Moreover this paper is also reporting that irradiation by swift heavy ion has changed the transmission of the ITO films, and its values decreases as compared to pristine (ITO) which degraded the performance of DSSC. Consequently, a very small value of absorbance is reported for ITO film. However, the absorbance of TiO₂ film has found to increase with irradiation of oxygen ion at fluence of 1x10¹² ions/cm² and decreased at 5x10¹² ions/cm². It is also confirmed that the absorbance of TiO₂ film and TiO₂/ITO photoanode increases with irradiation of oxygen ion at fluence of 1x10¹² ions/cm² and decreased at 5x10¹² ions/cm².  The band gap values of TiO₂ thin film were obtained to have a change from 3.37 eV (for pristine) to 3.44 eV at 5x10¹² ions/cm². But the decrease in band gap is also found 3.17 eV at fluence of 1x10¹² ions/cm². However, N719 dye loaded O⁷⁺ (1x10¹² ions/cm²) irradiated TiO₂ film show high absorption as compared to other samples. Thus the dose of O⁷⁺ irradiation at fluence 1x10¹² ions/cm² may fabricate more efficient DSSC and consequently future prospective of such type of photoanode materials for dye sensitized solar cells seems to be bright.

Keywords

Swift heavy ion irradiation, energy losses, dye-sensitized solar cells, optical properties of TiO₂ /and ITO thin films, TiO₂ / ITO photoanode.