Chemical post-treatment and thermoelectric properties of poly(3,4-ethylenedioxylthiophene):poly(styrenesulfonate) thin films

Abstract

We report on the modification of the thermoelectric properties of poly(3,4-ethylenedioxylthiophene):poly(styrenesulfonate) (PEDOT:PSS) thin films by means of a simple post treatment of the solid thin films realized by drop-coating. We show that the organic polar solvents, dimethyl sulfoxide and ethylene glycol as secondary dopants for PEDOT:PSS, only affect the film morphology for which a high electrical conductivity is observed. In contrast, ethanolamine (MEA) and ammonia solutions are reduction agents that improve the density of PEDOT chains in the reduced forms (polaron and neutral states), resulting in the trade-off between Seebeck coefficient and electrical conductivity. Furthermore, we show that the nature of amines determines the reduction degree: the nitrogen lone pair electrons in MEA are easier to be donated than those in ammonia solution and will therefore neutralize the PEDOT chains

Optical properties and conductivity of PEDOT:PSS films treated by polyethylenimine solution for organic solar cells

“…The reduction of T is associated to the A increase in this spectral region. The increase of the A band centered at 900 nm is associated with electron transfer to oxidized PEDOT chains from PEI, which also supports the conductivity reduction results [27,[30][31][32]. Fig.…”

Effect of incorporation of ethylene glycol into PEDOT:PSS on electron phonon coupling and conductivity

“…A common method that is used to improve the properties of PEDOT:PSS is a chemical treatment that involves the addition of co-solvents, which results in considerable improvement to the polymer's conductivity. 1,[13][14][15][16][17] However, PEDOT:PSS exhibits strong electron-phonon coupling, 18,19 which results in the low carrier mobility at room temperature. 20 While the electron-phonon coupling in inorganic semiconductors is rather weak, in their narrow-band organic counterparts it plays a prominent role.…”

Effective Approaches to Improve the Electrical Conductivity of PEDOT:PSS: A Review

“…[ 82 ] Except organic solvent EG, reduction agents such as hydrazine (HZ), ethanolamine (MEA), and ammonia solutions were used for de-doping, unfortunately, the conductivity of PEDOT:PSS (Clevios PH 1000) (DMSO or EG-mixed) fi lm was decreased. [ 83,84 ] In addition, EG post-treated PEDOT:PSS (glycerol-mixed) fi lms reached conductivity of over 1000 S cm −1 , as reported by Palumbiny et al [ 85 ] In particular, DeLongchamp and co-workers treated PEDOT:PSS (Clevios P) fi lm by a water rinse. [ 86 ] As a result of PSS removal, the fi lm thickness is reduced by 35%, and the conductivity is increased by 50% from 0.4 to 0.6 S cm −1 .…”