PEDOT:PSS buffer layers have been processed with the standard annealing step used for organic solar cells device applications. The d.c. conductivity σ as a function of temperature for two heating rates under He and a...PEDOT:PSS buffer layers have been processed with the standard annealing step used for organic solar cells device applications. The d.c. conductivity σ as a function of temperature for two heating rates under He and atmospheric air was studied. Moreover, the stability of the conductivity was investigated at different temperatures and environments vs time. The main results can be summarized in the following: the increase of σ due to the thermal activation of the carriers and the improvement of the crystallinity compete with the decrease of σ resulting from the irreversible structural degradation of the polymer chains promoted by the oxygen and moisture of the atmospheric air. The heat treatment time and the temperature at which the two competing mechanisms result in a maximum of the electrical conductivity have been determined and results are discussed relevant to organic optoelectronic devices containing PEDOT: PSS buffer layers.展开更多
The conductivity difference Δσ between two similar PEDOT:PSS films, 120 nm thick, heated by 5 and 15 K/min from 80 to 440 K, the one under inert He and the other under ambient air gives an approximate measure of the...The conductivity difference Δσ between two similar PEDOT:PSS films, 120 nm thick, heated by 5 and 15 K/min from 80 to 440 K, the one under inert He and the other under ambient air gives an approximate measure of the influence of oxygen and moisture on the conductivity vs temperature T. The resulting curves Δσ = f(T) exhibit three different regions: at temperatures from 80 to 145 K for heating rate 5 K/min and from 80 to 200 K for 15 K/min, an intense degradation of the sample under ambient atmosphere was revealed by the abrupt increase of the difference of the conductivities between He and atmospheric air. At intermediate temperatures from 145 to 380 K for 5 K/min and 200 to 400 K for 15 K/min, the conductivity difference remains basically constant indicating a stabilization of the damage produced by oxygen and moisture. Finally, for temperatures higher than 380 to 400 K the degradation increases again. An explanation of this behavior is proposed based on the hydrophilic character of the PSS and the destructive role of oxygen at high temperatures. Moreover, the isotherms σ = σ(t), where t is the heating time, at 443 K, under inert He and under atmospheric air for one hour verify the significant role of oxygen and moisture on the electrical conductivity. Under He the conductivity increases monotonically with t, but under ambient air factors the conductivity competes with others decreasing it producing a maximum at about t = 10 min.展开更多
文摘PEDOT:PSS buffer layers have been processed with the standard annealing step used for organic solar cells device applications. The d.c. conductivity σ as a function of temperature for two heating rates under He and atmospheric air was studied. Moreover, the stability of the conductivity was investigated at different temperatures and environments vs time. The main results can be summarized in the following: the increase of σ due to the thermal activation of the carriers and the improvement of the crystallinity compete with the decrease of σ resulting from the irreversible structural degradation of the polymer chains promoted by the oxygen and moisture of the atmospheric air. The heat treatment time and the temperature at which the two competing mechanisms result in a maximum of the electrical conductivity have been determined and results are discussed relevant to organic optoelectronic devices containing PEDOT: PSS buffer layers.
文摘The conductivity difference Δσ between two similar PEDOT:PSS films, 120 nm thick, heated by 5 and 15 K/min from 80 to 440 K, the one under inert He and the other under ambient air gives an approximate measure of the influence of oxygen and moisture on the conductivity vs temperature T. The resulting curves Δσ = f(T) exhibit three different regions: at temperatures from 80 to 145 K for heating rate 5 K/min and from 80 to 200 K for 15 K/min, an intense degradation of the sample under ambient atmosphere was revealed by the abrupt increase of the difference of the conductivities between He and atmospheric air. At intermediate temperatures from 145 to 380 K for 5 K/min and 200 to 400 K for 15 K/min, the conductivity difference remains basically constant indicating a stabilization of the damage produced by oxygen and moisture. Finally, for temperatures higher than 380 to 400 K the degradation increases again. An explanation of this behavior is proposed based on the hydrophilic character of the PSS and the destructive role of oxygen at high temperatures. Moreover, the isotherms σ = σ(t), where t is the heating time, at 443 K, under inert He and under atmospheric air for one hour verify the significant role of oxygen and moisture on the electrical conductivity. Under He the conductivity increases monotonically with t, but under ambient air factors the conductivity competes with others decreasing it producing a maximum at about t = 10 min.
