TY - JOUR
T1 - Length-scale effects on electrical and thermal transport in polyaniline thin films
AU - Jin, Jiezhu
AU - Wang, Qing
AU - Haque, M. A.
N1 - Funding Information:
M.A. Haque gratefully acknowledges the support from the Korea Institute of Machinery & Materials and the National Science Foundation ( CMMI 0555420 ).
PY - 2010/1
Y1 - 2010/1
N2 - Conducting polymers are prevalently used in organic and flexible electronics and energy conversion devices. While their thermo-physical properties are well characterized for different processing and doping conditions, very little is known about the effect of length-scale, especially their thermal conductivity and thermal contact resistance of their interfaces with substrates. In this paper we develop an analytical model to capture the heat transfer in ultra-thin polyaniline thin films and their interfaces with other substrate materials. The model is demonstrated on 20-1000 nm thick 50% camphor-sulphonic acid doped polyaniline films patterned on silicon substrate using photolithography and reactive ion etching. The four-probe based technique allows simultaneous electrical and thermal characterization. Experimental results show a 500% and 200% increase in the in-plane thermal conductivity and electrical conductivity, respectively as the film thickness is increased from 20 nm to 1000 nm. These findings suggest up to 300% improvement in thermoelectric performance for 20 nm thick films when compared to the bulk. Such strong length-scale effects are observed to decay rapidly after 100 nm film thickness and can be attributed to the enhanced phonon scattering at the surface and interface boundaries at length-scales comparable to phonon mean free paths.
AB - Conducting polymers are prevalently used in organic and flexible electronics and energy conversion devices. While their thermo-physical properties are well characterized for different processing and doping conditions, very little is known about the effect of length-scale, especially their thermal conductivity and thermal contact resistance of their interfaces with substrates. In this paper we develop an analytical model to capture the heat transfer in ultra-thin polyaniline thin films and their interfaces with other substrate materials. The model is demonstrated on 20-1000 nm thick 50% camphor-sulphonic acid doped polyaniline films patterned on silicon substrate using photolithography and reactive ion etching. The four-probe based technique allows simultaneous electrical and thermal characterization. Experimental results show a 500% and 200% increase in the in-plane thermal conductivity and electrical conductivity, respectively as the film thickness is increased from 20 nm to 1000 nm. These findings suggest up to 300% improvement in thermoelectric performance for 20 nm thick films when compared to the bulk. Such strong length-scale effects are observed to decay rapidly after 100 nm film thickness and can be attributed to the enhanced phonon scattering at the surface and interface boundaries at length-scales comparable to phonon mean free paths.
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U2 - 10.1016/j.orgel.2009.09.018
DO - 10.1016/j.orgel.2009.09.018
M3 - Article
AN - SCOPUS:72649094471
VL - 11
SP - 29
EP - 35
JO - Organic Electronics: physics, materials, applications
JF - Organic Electronics: physics, materials, applications
SN - 1566-1199
IS - 1
ER -