Preparation of chalcogenide thin films using electrodeposition method for solar cell applications - A review

摘要

The use of chalcogenide materials for thin film solar cell applications has increased recently because of their interesting properties. Chalcogenide materials, such as cadmium telluride, copper indium gallium (di) selenide and copper zinc tin sulfide have absorption coefficient values greater than 10(4) cm(-1) with direct band gap values close to 1.5 eV, which are desirable for absorber material of thin film solar cells. Chalcogenide materials like cadmium sulfide are commonly used as window layer in thin film solar cells. Though various deposition techniques like chemical bath deposition, chemical vapor deposition are available for chalcogenide thin film formation, electrochemical deposition is preferred because of certain advantages, such as easy scalability and simple operating conditions. This review focuses on the electrodeposition of different chalcogenide materials by potentiostatic, galvanostatic, pulsed potential or pulsed current modes. Stoichiometric deposits can be achieved by controlling the pH, precursor concentration, deposition potential and the temperature of the electrolytic bath. Deposits of both p-type and n-type conductivity can be prepared from electrodeposition route, by suitably adjusting the deposition potential. Implementation of recent techniques, such as multistep underpotential deposition for chalcogenide thin film formation, has eliminated the need for high-temperature annealing after the deposition process. Similarly, the problem of narrow working potential range in the case of aqueous electrolyte has been solved with the use of ionic liquid based electrolytes. Solar cells fabricated out of electrodeposited chalcogenides thin films have presented maximum conversion efficiency of 12.6%.