Improving Performance of CIGS Solar Cells by Annealing ITO Thin Films Electrodes

Abstract

Indium tin oxide (ITO) thin films were grown on glass substrates by direct current (DC) reactive magnetron sputtering at room temperature. Annealing at the optimal temperature can considerably improve the composition, structure, optical properties, and electrical properties of the ITO film. An ITO sample with a favorable crystalline structure was obtained by annealing in fixed oxygen/argon ratio of 0.03 at 400°C for 30 min. The carrier concentration, mobility, resistivity, band gap, transmission in the visible-light region, and transmission in the near-IR regions of the ITO sample were-1.6E+20 cm−3,2.7E+01 cm2/Vs,1.4E-03 Ohm-cm, 3.2 eV, 89.1%, and 94.7%, respectively. Thus, annealing improved the average transmissions (400–1200 nm) of the ITO film by 16.36%. Moreover, annealing a copper-indium-gallium-diselenide (CIGS) solar cell at 400°C for 30 min in air improved its efficiency by 18.75%. The characteristics of annealing ITO films importantly affect the structural, morphological, electrical, and optical properties of ITO films that are used in solar cells.

Synergistic Influence of the Deposition Method, Postdeposition Annealing, and Textured Substrates on the Properties of ITO Thin Films

“…Postdeposition annealing has also been considered for enhancing the optical transmittance. A maximum transmittance of 89.16% from 77.14% at 400 °C has been achieved through postdeposition annealing . By improving the transmittance of ITO in a device such as solar cells, the photon management or in-coupling of photons into the active layer will be improved.…”

“…A maximum transmittance of 89.16% from 77.14% at 400 °C has been achieved through postdeposition annealing. 11 By improving the transmittance of ITO in a device such as solar cells, the photon management or in-coupling of photons into the active layer will be improved. Also, patterning with random and periodical structures tends to improve the light trapping efforts.…”