Nanocomposites and nanomaterials

Composite polymer films with semiconductor nanocrystals for organic optoelectronics
Pylypova O.1, Evtukh A.1,2, Shmahlii S.2, Korbutyak D.2, Tokarev V.3
1Taras Shevchenko National University of Kyiv, Institute of High Technologies, Kyiv, Ukraine. E-mail: steblolia@gmail.com
2 V. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine 41 pr. Nauki, 03028, Kyiv, Ukraine.
3 Lviv Polytechnic National University, 79013, Lviv, Ukraine.

Cadmium sulphide (CdS) is one of the cheapest semiconducting material. The deposition and characterization of CdS semiconducting thin films has been received a considerable amount of interest due to their potential application in the area of electronic and opto-electronic devices fabrications such as solar cells, photoconductor, laser material, optical wave-guide, and non-linear integrated and optical device [1]. The purpose of this paper is to investigate the electric conductivity of composite polymer films under the influence of light and without it, in order to determine their prospects for organic optoelectronics. The formation of thin polymeric films with integrated composite nanocrystals (Cd:Cu)S was carried out in several stages. At the first stage, the growth of a reactive copolymer, modified with demethylaminoethanol, polyethyleneglycol in an amount of 10% of copolymer weight and a mixture of cadmium acetate Cd(Ac)2 with copper acetate Cu(Ac)2 in dimethylformamide at ratios [Cd(Ac)2]: Cu(Ac)2] = 99:1  90:10 was performed. The content of Cd(1-x)CuxS in the film is 20%. Thin polymeric films were deposited on glass plate from obtained solution by the spin coating method. The average thickness of the obtained films was of 20 nm. The structuring of the films was occurred at annealing (T = 363-393K). At the final stage CdS and CuS nanocrystals were formed in the polymer film as a result of treatment of the films with hydrogen sulfide (H2S) from the gas phase. The current-voltage characteristics of composite films with different ratios of CdS and CuS nanocrystals without and under irradiation have been measured. The conductivity of composite polymer based films as under illumination and without does not depend on the ration of CdS and CuS nanocrystals. The mechanism of electron transport at measurement without illumination is direct tunneling. But under illumination the the Poole-Frenkel electron transport mechanism is realized. In this case the potential barrier is φb=0.46 eV for film with 40% CdS:60% CuS and φb = 0.5 eV for film with 0% CdS:100% CuS. 
  1. D. J. Desale, S. Shaikh, F. Siddiqui, A. Ghosh, R. Birajdar, A. Ghule, R. Sharma, // Pelagia Research Library: Advances in Applied Science Research.-2011.-2.-P.417-425