The Band Structures of Zn1−xMgxO(In) and the Simulation of CdTe Solar Cells with a Zn1−xMgxO(In) Window Layer by SCAPS

Abstract

Wider band-gap window layers can enhance the transmission of sunlight in the short-wavelength region and improve the performance of CdTe solar cells. In this work, we investigated the band structure of In-doped Zn1−xMgxO (ZMO:In) by using first-principles calculations with the GGA + U method and simulated the performance of ZMO:In/CdTe devices using the SCAPS program. The calculation results show that with the increased Mg doping concentration, the band gap of ZMO increases. However, the band gap of ZMO was decreased after In incorporation due to the downwards shifted conduction band. Owing to the improved short circuit current and fill factor, the conversion efficiency of the ZMO:In-based solar cells show better performance as compared with the CdS-based ones. A highest efficiency of 19.63% could be achieved owing to the wider band gap of ZMO:In and the appropriate conduction band offset (CBO) of ~0.23 eV at ZMO:In/CdTe interface when the Mg concentration x approaches 0.0625. Further investigations on thickness suggest an appropriate thickness of ZMO:In (x = 0.0625) in order to obtain better device performance would be 70–100 nm. This work provides a theoretical guidance for designing and fabricating highly efficient CdTe solar cells.

Performance simulation of solar cell based on AZO/CdTe heterostructure by SCAPS 1D software

“… Solar Cell structure Voc (V) Jsc FF PCE (%) Ref. n -ZnO/CdTe 0.54 19.5 0.72 8.8 [ 10 ] FTO/MZO/CdTe/Te 0.80 23.4 0.62 11.8 [ 41 ] FTO/MZO/CdTe/Au 0.86 25.5 0.73 16.1 [ 13 ] FTO/MZO/CdTe/ZnTe: Cu/Au 0.85 28.16 0.81 19.63 [ 25 ] FTO/MZO/CdTe/Au 0.84 25.8 0.76 16.61 [ 42 ] AR Coating/FTO/MZO/CdTe/Te 0.86 26.8 0.79 18.03 [ 43 ] …”

“…ZnO can be doped n-type through an extrinsic dopant such as Aluminum (group III), which replaces the cations; being Aluminum one of the most suitable dopants in ZnO thin films because it has a lower ionic radius (Al = 57 p.m.) than that Zinc (Zn = 83 p.m.) generating a better coupling with it [ 11 ]. Compared to the traditional CdS window layer, Aluminum-doped zinc oxide (AZO) offers several advantages for CdTe-based thin-film solar cells among them decrease the parasitic optical absorption of the window layer, which is favorable to improve the short-circuit current (Jsc) [ 25 ]. Also, AZO consists of non-toxic, cheap, and abundant elements in nature, which reduces its production cost, and it can be synthesized with different processes such as chemical vapor deposition, spray pyrolysis, pulsed-laser deposition, sol-gel process, sputtering, being the latter preferred for large-scale production [ 22 , 40 ].…”

Te/CdTe and Al/CdTe Interfacial Energy Band Alignment by Atomistic Modeling

“…The key parameters of the SCAPS-1D setup is found in Table for the CdTe-based PV device arrangement (Figure ). Appropriate modeling parameters that were not obtained using the DFT+GF method were collected from published device simulation-based literature − and used in the current work. A series and shunt resistance of 1 Ω·cm –2 and 10 3 Ω·cm –2 , respectively, were used since they are typical of CdTe-based solar cells.…”

Optimization of Thin-Film Carbon Nitride (C2N) based solar cell via Zn1−xMgxO as a buffer layer

“…The solar cell input parameters for simulations are summarized in Table 1, as extracted from [22,24,[29][30][31][32]. For interface layers, the SCAPS-1D default values are shown in Table 2.…”