2022/02/22 by Mohit Sood, Sood, Mohit, Poorani Gnanasambandan +11
Engineering · Materials Science · #Applied Physics (physics.app-ph) #Chalcogenide Semiconductor Thin Films #Copper-based nanomaterials and applications #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Quantum Dots Synthesis And Properties
paper · pdf · doi:10.48550/arxiv.2202.10708
openalex publication_date 2022/02/22 · openalex created_date 2022/04/03 · openalex updated_date 2026/07/28
Traditional CdS buffer layer in selenium-free Cu(In,Ga)S2 solar cells leads to reduced open-circuit voltage because of a negative conduction band offset at the Cu(In,Ga)S2/CdS interface. Reducing this loss necessitates the substitution of CdS by an alternative buffer layer. However, the substitute buffer layer may introduce electrical barriers in the device due to unfavorable band alignment at the other interfaces such as between buffer/ZnO i-layer. This study aims to reduce interface recombinations and eliminate electrical barriers in Cu(In,Ga)S2 solar cells using a combination of Zn1-xMgxO and Al-doped Zn1-xMgxO buffer and i-layer combination deposited using atomic layer deposition and magnetron sputtering, respectively. The devices prepared with these layers are characterized by current-voltage and photoluminescence measurements. Numerical simulations are performed to comprehend the influence of electrical barriers on the device characteristics. An optimal composition of Zn1 xMgxO x = 0.27 is identified for a suitable conduction band alignment with Cu(In,Ga)S2 with a bandgap of ~1.6 eV, suppressing interface recombination and avoiding barriers. Optimized buffer composition together with a suitable i-layer led to a device with 14 % efficiency and an open-circuit voltage of 943 mV. A comparison of optoelectronic measurements for devices prepared with ZnO and Al:(Zn,Mg)O shows the necessity to replace the ZnO i-layer with Al:(Zn,Mg)O i-layer for a high-efficiency device.