Mansour, Ahmed E. Kim, Hongwon Park, Soohyung Schultz, Thorsten Cao, David Xi Nguyen, Thuc-Quyen Bruetting, Wolfgang Opitz, Andreas Koch, Norbert 2024-01-19T16:32:18Z 2024-01-19T16:32:18Z 2021-09-02 2020-10 2199-160X https://pubs.kist.re.kr/handle/201004/118052 Solution-processed conducting polymer thin films are key components in organic and flexible electronic and optoelectronic devices. An archetypal conducting polymer is poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), which can feature a high work function and thus helps achieving Ohmic contacts for holes with many semiconductors. However, it is known that residual water in PEDOT:PSS films lowers their work function and is detrimental for device lifetime. Our photoelectron spectroscopy experiments reveal that the work function of PEDOT:PSS films containing residual water shows the same trend as function of temperature as does the dielectric constant (e) of water, in the range between 25 degrees C and -100 degrees C. Consistently, it is found from impedance spectroscopy measurements that e of residual water containing PEDOT:PSS films increases with decreasing temperature. After removal of residual water from PEDOT:PSS films by annealing in ultrahigh vacuum, the work function of thin films is much higher than before (reaching 6.1 eV) and, notably, independent of temperature. In contrast, no indication is found that the presence of residual water has any impact on the electrical conductivity. For a nominally water-free molecularly doped conjugated donor/acceptor copolymer films, a correlation between sample work function and temperature similar to those seen for PEDOT:PSS is found. English WILEY ENERGY-LEVEL ALIGNMENT DOPED POLY(3-HEXYLTHIOPHENE) ELECTRICAL-CONDUCTIVITY CHARGE-TRANSFER SOLAR-CELLS PEDOT-PSS FILM INTERFACE PERFORMANCE MORPHOLOGY Conductive Polymer Work Function Changes due to Residual Water: Impact of Temperature-Dependent Dielectric Constant Article 10.1002/aelm.202000408 1 ADVANCED ELECTRONIC MATERIALS, v.6, no.10 ADVANCED ELECTRONIC MATERIALS 6 10 scie scopus 000567838800001 2-s2.0-85090789082 Nanoscience & Nanotechnology Materials Science, Multidisciplinary Physics, Applied Science & Technology - Other Topics Materials Science Physics Article ENERGY-LEVEL ALIGNMENT DOPED POLY(3-HEXYLTHIOPHENE) ELECTRICAL-CONDUCTIVITY CHARGE-TRANSFER SOLAR-CELLS PEDOT-PSS FILM INTERFACE PERFORMANCE MORPHOLOGY conductive polymers dielectric constant temperature dependence water work function