Reduction of recombination current in CdTe/CdS solar cells

Abstract

A study of the current–voltage behavior of recombination current in CdTe/CdS solar cells has shown that the reverse saturation current, J0, and the diode quality factor, A, are correlated. Our better devices typically have low values of both A and J0. Spectral response data indicate that devices with a gradual decline in quantum efficiency beginning at about 600 nm show better performance than devices with a sharp drop at the CdS band gap of 510 nm, which is interpreted as an indication that mixing between CdS and CdTe during processing reduces the amount of recombination current at the interface.

Thin-Film Cadmium Sulfide/Cadmium Telluride Alloys

“…Evidence that the commonly used recrystallization heat treatment in the presence of CdC1 2 at 400-430'C promotes interdiffusion between the CdTe and CdS layers in CdTe/CdS solar cells has been reported by several groups [1][2][3][4]. A quantitative understanding of the interdiffusion process requires knowledge of the properties of the CdTe-CdS alloy system.…”

Ellipsometric investigation of S–Te inter-diffusion and its effect on quantum efficiency of CdS/CdTe thin films solar cell

“…On the other hand, we find that the devices produced with high temperature process of CdTe deposition typically exhibit slow drops in EQE at the CdS band gap as well as our experimental data. The graded absorption due to the inter-mixing of CdS and CdTe is believed to be the reason (Oman et al, 1995).…”

“…Thus inter-diffusion at the CdS/CdTe junction is generally considered to have an influence on the photocurrent. Experimental and theoretical studies show that mixing of CdS and CdTe reduces the amount of recombination current at the CdS/CdTe junctions and consequently increases photocurrent (Oman et al, 1995;Brus, 2012;Mathew et al, 2012).…”

Sulfur Diffusion In Polycrystalline Thin-Film CdTe Solar Cells

“…Interdiffusion of the CdTe and CdS with the formation of CdTe 1-x S x ternary phases occurs as a result of the anneal. [1][2][3][4][5][6] For CdTe deposition techniques which involve deposition temperatures in excess of 400°C, interdiffusion is also observed as a result of the growth process itself. 3 This interdiffusion has profound and complicated effects on the ultimate performance of the resulting device.…”

“…Passivation of defects in the CdTe by the S has also been suggested to occur. 6 It is clearly important to be able to characterize, and ultimately control, this interdiffusion process.…”