A new method for CdSexTe1-x band grading for high efficiency thin-absorber CdTe solar cells

An overview on the role of ZnTe as an efficient interface in CdTe thin film solar cells: a review

“…59 To improve the performance to CdTe-based solar cells, in recent years, researchers have mainly focused on two features including replacement of the traditional CdS window layer by a wide band gap and fully transparent material such as Zn 1Àx Mg x O (ZMO) [60][61][62][63] for advancement in photocurrent and the introduction of Se in CdTe to form a graded band gap CdSeTe/CdTe absorber, which can passivate the front surface to increase the carrier lifetime and absorption in the longer wavelength region simultaneously. 64 An efficiency of B16% was reported by Samoilenko et al 65,66 by using a magnesium-doped zinc oxide (MZO) window layer in CdTe solar cells. The introduction of Se in the form of a CdSeTe layer at the interface with magnesium-doped zinc oxide (MZO) resulted in a PCE of 18.6% 61 and B19% 67 under similar conditions.…”

“…The developed devices demonstrated almost similar performances with the maximum PCE of 14.5% for the Au contact. 212 As stated, strong progress in the power conversion efficiency of CdTe solar cells has been recorded for devices with an MZO optical window instead of the conventional CdS by introducing a CdSeTe supporting absorber together with CdTe by modifying the architecture, 64,66,67 causing the highest PCE of 22.1%. 32,69,70 Efforts have also been made to overcome the back contact issues by doping the ZnTe layer with copper to enhance its performance and thickness evolution of ZnTe, where Cu deposited via the rf sputtering route at 200 1C substrate temperature with the device structure of glass/FTO/ZnO/CdTe/ZnTe:Cu/Au.…”

“…In recent years, a higher power conversion efficiency has been attained with enhanced J sc by introducing a lower band gap CdSeTe supporting absorber as an interface and replacing CdS with a more transparent and wider band gap material, i.e., Mg x Zn 1Àx O (MZO). 64,66,67 As stated, MZO is a promising alternative to replace the CdS window layer in CdTebased solar cells and its electron density can be tuned, which provides flexibility in controlling the conduction band offset together with the recombination rates at the TCO/MZO and MZO/Cd(Se)Te interfaces, where the CdTe absorber layer is engineered by employing graded band gap Se (Selenium) insertion to the latter interface. 59,70 The ZnTe semiconducting layer acts as an interface layer between the CdTe absorber and rear-metal contact, which limits the recombination losses dealing with minority carriers due to its captivating performance.…”

“…Fig.5Pictorial view of the unit cell of the ZnTe and device architecture comprised of ZnTe as the back contact, where the CdS optical window is replaced by an MZO layer 65,66. …”

Analysis of Se Co-evaporation and Post-selenization for Sb2Se3-Based Solar Cells

“…The reduced detectability of CdS peaks, culminating in their almost total suppression in the post-selenized samples, suggests that there is a decomposition of the window layer at the junction due to the increased presence and diffusion of Se in the layer. In addition, in a previous study on CdSe x Te 1– x -based solar cells, we have already proven the degradation of CdS after the selenization of the layer above it. Moreover, the collapse of the EQE response occurs between 750 and 700 nm, which is the wavelength region corresponding to the band gap of CdSe (around 1.72 eV), indicating the possible formation of this not photoactive compound at the junction .…”