The effects of the PEDOT:PSS acidity on the performance and stability of P3HT:PCBM-based OSCs

• Published in: Journal of materials science. Materials in electronics 2018-11, Vol.29 (22), p.19287-19295
• Main Authors: Kadem, Burak Y., Al-Hashimi, Mohammed, Hasan, Ali S., Kadhim, Raheem G., Rahaq, Yaqub, Hassan, Aseel K.
• Format: Article
• Language: English
• Subjects: Ammonium hydroxide; Caustic soda; Characterization and Evaluation of Materials; Chemistry and Materials Science; Circuits; Electrical resistivity; Energy conversion; Materials Science; Moisture absorption; Morphology; Open circuit voltage; Optical and Electronic Materials; Photovoltaic cells; Physical properties; Polymers; Short circuit currents; Stability; Transmittance; Transport
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-018-0055-4

The optical transmittance, electrical conductivity and morphology of PEDOT:PSS treated with ammonium hydroxide (NH 4 OH) have been investigated. Transmittance spectra of spun PEDOT:PSS layers were enhanced slightly as a result NH 4 OH treatment while surface of the films has exhibited variation in the roughness and an increase in the electrical conductivity. Improvement in the physical properties of PEDOT:PSS is shown to be the key factor in enhancing the power conversion effeciency (PCE) with values as high as 4% associated with high fill factor (FF) of 57%, open circuit voltage (V OC ) of 0.64 V and larger short circuit current density (J SC ) of 11 mA cm −2 . Stabiltiy test of the devices has been carried out over a period of 2 months, when a device incorporating PEDOT:PSS with pH ~ 4 as the hole transport layer has shown an improved stability with a degredation in PCE in about 43% whereas J SC has decreased in about 20% compared to a device incorporating pristine PEDOT:PSS with PCE decreased in about 66% and J SC in about 50% over the stated period of test. These effects have been ascribed to the increased acidity of the hole transport layer.