Electrochemical Deposition of Hybrid Material Based on Polyindole and CdTe/CdS

The application of hybrid materials based on the organic and inorganic films in photovoltaic cells  offers significant advantages. Solar cells built this way are inexpensive to fabricate, can be used on flexible substrates and can be easily shaped. In this work the polyindole (PIN) was used as the matrix for deposition of inorganic semiconductor CdTe, which enables absorption of light in the visible region of solar spectrum, where the solar spectrum has the highest intensity. This feature is linked to the band gap energy of CdTe (E_g=1.4 eV) and high absorption coefficient. Widespread use of CdTe in photoelectrochemical solar cells is however limited by several factors such like susceptibility to photocorrosion in aqueous electrolytes, further hindering their application. The PIN matrix made as well-oriented wires was used to prevent CdTe against photocorrosion.

The results of the influence of electrochemical deposition conditions on the properties of hybrid material are presented. The polyindole was electrodeposited into the membranes to form well-oriented polymer matrix. The size of nanowires and their packing were varied by monomer concentration and time. The CdTe films were obtained electrochemically and chemically into and on the top of PIN nanowires. Initially, the polyindole properties such as electrochemical behavior in different solutions, wires morphology and structure were investigated by various techniques. After that, CdTe modification of the hybrid was studied by different techniques as well. The morphology was explored by Scanning Electron Microscopy, the chemical composition was investigated by Raman and IR spectroscopy. The UV-vis spectrometry was used to estimate the band gap energy of hybrid. It was found that size and packing of PIN nanowires determines the morphology of CdTe into and on the top wires. The chemical composition and doping type depends on the deposition parameters such as bath composition and ions concentration, deposition time and potential. The photoelectrochemical measurements carried out in polysulphide solution showed that application of polyindole layer improved the photostability of CdTe and increased the value of photocurrent.