Properties and mechanism of solar absorber CdTe thin film synthesis by unipolar galvanic pulsed electrodeposition

Abstract

Electrochemical deposition of CdTe semiconductor thin films over transparent conducting glass substrates by sequential unipolar current pulses is described. The magnitude of pulsed current and pulse periodicity affects the crystalline structure, morphology, optical absorbance and composition of CdTe films. CdTe films formed under high magnitude pulsed current density *5-15 mA cm -2 are crystalline with dominant cubic structure having (111) plane oriented parallel to the substrate. Stoichiometric CdTe film growth occurs with current pulses of short 25-300 ms periodicity and 3-50 ms duration. A mechanism of the CdTe growth involving in situ cathodic tellurization process step involving H 2 Te formation and reaction with electrochemically deposited Cd monolayer is described. CdTe film growth in the pulsed electrodeposition occurs under mass transport conditions under strong influence of high magnitude pulsed current. This results in much higher growth rates *5-8 lm h -1 for CdTe films which is attractive for CdTe solar cells in a production environment.

Electrodeposition Fabrication of Chalcogenide Thin Films for Photovoltaic Applications

“…CdTe, a direct-band-gap material with a band gap of 1.54 eV, is another important cadmium chalcogenide than has been widely used for photovoltaic devices. In most of the reports, the electrodeposition fabrication of CdTe was conducted at a constant potential using an aqueous electrolyte with an acidic medium [61][62][63]. The following are the reactions occurring at the cathode where the CdTe is deposited [62,64,65]:…”

“…In most of the reports, the electrodeposition fabrication of CdTe was conducted at a constant potential using an aqueous electrolyte with an acidic medium [61][62][63]. The following are the reactions occurring at the cathode where the CdTe is deposited [62,64,65]:…”

“…where, E 0 is the standard deposition potential, and ∆G 0 is the Gibbs free energy of formation. According to the deposition potentials for Cd and Te, it can be seen that more negative potentials may result in an increase in the Cd concentration and more positive potentials may lead to the formation of a Te-rich CdTe film [62]. It has been reported that Cd-rich CdTe results in n-type conduction and Te-rich CdTe results in p-type conduction [66][67][68].…”

Properties of CuSbS2 thin films electrodeposited from ionic liquids as p-type absorber for photovoltaic solar cells

“…Electrodeposition under galvanostatic, potentiostatic and pulsed current techniques for the synthesis of thin films of binary semiconductors mainly, [23,24], [25], [26,27] and [28] have been widely employed in the past for the fabrication of thin film solar cells. Conventionally, the electrodeposition of semiconductor films has been carried out from aqueous or organic electrolytes.…”

Electrochemical Synthesis of Well-Dispersed CdTe Nanoparticles on Reduced Graphene Oxide and Its Photoelectrochemical Sensing of Catechol

“…During the cathodic scan, a current plateau that ranged from−0.7 V to −0.5 V appeared following the cathodic peak (approximately E = −0.3 V) caused by the reduction of Te (IV). Many studies [39][40][41][42] have reported that CdTe films are formed in this potential range in accordance with the following reaction: Cd 2+ + Te +2e → CdTe. Based on the above analysis, −0.6 V was selected as the deposition potential for CdTe.…”