Effect of organic solar cells using various power O2 plasma treatments on the indium tin oxide substrate

Jhong-Ciao Ke; Yeong-Her Wang; Kan-Lin Chen; Chien-Jung Huang

doi:10.1016/j.jcis.2015.12.002

Effect of organic solar cells using various power O2 plasma treatments on the indium tin oxide substrate

J Colloid Interface Sci. 2016 Mar 1:465:311-5. doi: 10.1016/j.jcis.2015.12.002. Epub 2015 Dec 2.

Authors

Jhong-Ciao Ke¹, Yeong-Her Wang¹, Kan-Lin Chen², Chien-Jung Huang³

Affiliations

¹ Institute of Microelectronics, Department of Electrical Engineering, National Cheng-Kung University, #1 University Rd., Tainan, Taiwan.
² Department of Electronic Engineering, Fortune Institute of Technology, Kaohsiung 83160, Taiwan.
³ Department of Applied Physics, National University of Kaohsiung, Nanzih, Kaohsiung, Taiwan. Electronic address: chien@nuk.edu.tw.

PMID: 26688123
DOI: 10.1016/j.jcis.2015.12.002

Abstract

The effect of organic solar cells (OSCs) by using different power O2 plasma treatments on indium tin oxide (ITO) substrate was studied. The power of O2 plasma treatment on ITO substrate was varied from 20W to 80W, and the power conversion efficiency of device was improved from 1.18% to 1.93% at 20W O2 plasma treatment. The function of O2 plasma treatment on ITO substrate was to remove the surface impurity and to improve the work function of ITO, which can reduce the energy offset between the ITO and SubPc layer and depress the leakage current of device, leading to the shunt resistance increased from 897 to 1100Ωcm(2). The surface roughness of ITO decreased from 3.81 to 3.33nm and the work function of ITO increased from 4.75 to 5.2eV after 20W O2 plasma treatment on ITO substrate. As a result, the open circuit voltage and the fill factor were improved from 0.46 to 0.70V and from 0.56 to 0.61, respectively. However, the series resistance of device was dramatically increased as the power of O2 plasma treatment exceeds 40W, leading to the efficiency reduction. The result is attributed to the variation of oxygen vacancies in ITO film after the 60, 80W O2 plasma treatment. As a consequence, the power of O2 plasma treatment on ITO substrate for the OSCs application should be controlled below 40W to avoid affecting the electricity of ITO film.

Keywords: Indium tin oxide; O(2) plasma; Organic solar cell.