Germanium telluride as a BSF material for high efficiency ultra-thin CdTe solar cell

Abstract

The polycrystalline cadmium telluride (CdTe) is regarded as one of the leading photovoltaic (PV) materials for its high efficiency and low-cost. The absorber material CdTe has the ideal and direct bandgap of 1.45 eV and it has a high absorption co-efficient over 5×10 5 /cm. In this work, the possibility of ultra-thin absorber layer of CdS/CdTe solar cell was investigated by numerical analysis utilizing AMPS (Analysis of Microelectronic and Photonic Structures) simulator. In the proposed cell, the CdTe layer was reduced and found that 1 ȝm CdTe layer is enough for acceptable range of cell conversion efficiency. The viability of this ultra-thin CdTe absorber layer was examined, together with 0.1 ȝm GeTe back surface field (BSF) layer to reduce the barrier height in the valence band and to minimize the recombination losses at the back contact of the CdS/CdTe cell. It was found that the proposed ultra-thin cells have conversion efficiency of 18.68% (Jsc = 21.47 mA/cm 2 , FF = 0.85, Voc = 1.02 V) without BSF and with 100 nm GeTe BSF conversion efficiency increased to 22.53% (Jsc = 24.28 mA/cm 2 , FF = 0.875, Voc = 1.06 V) with only 0.8 ȝm of CdTe layer. Moreover, it was found that the normalized efficiency of the proposed cells linearly decreased with the increasing operating temperature at the gradient of -0.16%/°C, which indicated better stability of the proposed CdTe solar cell.

Room-temperature ferroelectric switching of spin-to-charge conversion in germanium telluride

“…36 ) and 4.80 eV (ref. 37 ), respectively), a downward band bending is expected at the interface, resulting in an inward built-in electric field (Fig. 1a, inset).…”

“…The latter dominates because of the larger difference in work functions/electron affinities (χ GeTe = 4.80 eV, χ p-Si(111) = 4.00 eV and ϕ Fe(111) ≈ 4.81 eV) (refs. 36,37 ) and the relatively low doping of Si, which determines a wider Schottky barrier. Therefore, the Si/GeTe interface provides an even more effective readout of the memory state, with a modulation of the resistance much larger (~4,000%) than that of Ti/GeTe.…”

Back contacts materials used in thin film CdTe solar cells—A review

“…Group IV tellurides are possible materials for back contacts. There are no known experimental studies of silicon telluride (Si 2 Te 3 ) or germanium telluride back contacts and only one numerical study 92 using AMPS software 93 on CdTe solar cells.…”

Numerical modeling of CdTe solar cells thin film investigation by using PC1D model

“…For more accurate and device modeling, CdTe/CdS needs around 50 parameters. To enhance the output performances of CdTe solar cells many optimizations based on effect of layer properties: thickness of the CdTe and CdS layers (Banerjee, 2015); defect density of the CdTe and CdS layers (Huang and Chuang, 2015); temperature impacts (Asaduzzaman et al, 2017b) and ultra-thin cells with BSF layers (Islam et al, 2011;Matin et al, 2013;Khosroabadi and Keshmiri, 2014;Dey et al, 2014;Ngoupo et al, 2015;Rahman et al, 2016;Sultana et al, 2017).…”