Two band theory and polarons conductivity in poly(ortho)anisidine Langmuir-Blodgett films

Sandro Carraraa, Riccardo Narizzanoa, Manoj Kumar Ramb, Claudio Nicolini a,b
 
 aInstitute of Biophysics, University of Genoa, Corso Europa 30, 16132 Genova, Italy
bFondazione El.B.A., Corso Europa 30, Genova, Italy
 
Poly(ortho)anisidine has become attractive material due to its ease in doping by protonic acid, conductivity, optical, electrochemical and chemical stability in doped and undoped states [1].

For many applications, it is desirable to have poly(ortho)anisidine in a thin films structure with known thickness and molecular packing [2].

In particular, conducting characteristics of Langmuir-Blodgett films prepared with such molecules have been investigated for the development of rechargeable battery, smart window, biosensors, gas sensors, corrosion protection and microelectronics devices [3].

Furthermore, thin films of poli(ortho)anisidine were found more promising due to their interesting optical and electrical properties [4]. In our earlier investigations, we reported the formation of Langmuir monolayers at different aqueous subphases and the UV-visible as well as electrical properties of the POAS LS films.

Dopant effects were investigated [5] and, moreover, direct comparisons between the electrical conductivity of Langmuir-Blodgett filmis prepared with poli(ortho)anisidine with their optical properties had showed correlation between the shift in the absorption bands and the conductivity of the films.

The aims of this work is to evaluate the behaviour of the conductivity of the films based on the polarons properties and the two band theory with the goal to demonstrate as the polarons motion inside the polimeric chains is in accordance with the motion of change carriers foreseen by the two band theory.

 

References

 [1] Y. Wei, W.W. Focke, G.E. Wnek, A. Ray and A.G. MacDiarmid, J. Phys. Chem., 93 (1989) 495.

 [2] N.E. Agbor, M.C. Petty, A.P. Monkman and H. Harris, Synth. Met. 55-53 (1993) 3789.

 [3] M. Pasqualli, G. Pistoia and R. Rosati, Synth. Met., 58 (1993) 1-5.

 [4] M.K. Ram, S. Paddeu, S. Carrara, E. Maccioni and C. Nicolini, Langmuir Vol.13, No 13 (1997), 2760-2765.

 [5] M. K. Ram, S. Carrara, S. Paddeu, and C. Nicolini, Thin Solid Films, 302 (1997) 89-97;