Optimization of organic solar cells with thin film Au as anode

• Published in: Solar energy materials and solar cells 2011-08, Vol.95 (8), p.2424-2430
• Main Authors: Yambem, Soniya D., Haldar, Amrita, Liao, Kang-Shyang, Dillon, Eoghan P., Barron, Andrew R., Curran, Seamus A.
• Format: Article
• Language: English
• Subjects: Applied sciences; Au thin films; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Energy; Exact sciences and technology; Natural energy; Organic photovoltaics; Photoelectric conversion; Photovoltaic conversion; Solar cells. Photoelectrochemical cells; Solar energy; Transparent electrode
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2011.04.019

Optical transmittance and conductivity for thin metallic films, such as Au, are two inversely related and extremely important parameters for its application in organic photovoltaics as the front electrode. We report our findings on how these parameters have been optimized to attain maximum possible efficiencies by fabricating organic solar cells with thin Au film anodes of differing optical transmittances and consequently due to scaling at the nanolevel, varying electrical conductivities. There was an extraordinary improvement in the overall solar cell efficiency (to the order of 49%) when the Au thin film transmittance was increased from 38% to 54%. Surface morphologies of these thin films also have an effect on the critical parameters including, V oc , J sc and FF. The efficiency of organic photovoltaic devices increases with the increase in transmittance of the thin Au film anode. However, after a certain transmittance the sheet resistance of the anode becomes very high and the efficiency starts to decrease. [Display omitted] ► Organic Photovoltaics were fabricated on thin Au films of varying transmittances (38–66%). ► All the critical parameters, namely the V oc , J sc and FF change with the change in transmittance and sheet resistance. ► Increase in transmittance increases the efficiency, reaches a maximum of 1.83% and then decreases. ► Surface morphology of the Au films influences the FF to a great extent.