Development of MnxCo0.015Zn1-xO electron transport layer for perovskite solar cells: Experimental and simulation study

Abstract

The electron transport layer (ETL) plays an important role in the performance and stability enhancement of perovskite solar cells (PSCs). Zinc oxide is considered a cost-effective and low-temperature processed ETL for PSCs, which offers decent mobility. However, the interface reaction occurs via a reaction of zinc oxide with the organic-inorganic metal hybrid halide perovskite absorber, which results in the degradation of the PSCs. To overcome this issue, metal doping was carried out. However, metal doping causes a reduction in the transmittance of the zinc oxide ETL layer because of high absorption. Thus, the overall performance of the PSCs was reduced due to the lessening of the photogenerated current. In this regard metal co-doping (Mn and Co) was done to improve the electrical as well as electronic properties. Furthermore, the influence of Mn doping on the structural, optical, and photoluminescence properties of MnxCo0.015Zn1-xO (x = 0, 0.002, 0.008, and 0.012) hexagonal nanosheets was investigated. X-ray diffraction results revealed that the inter-planar spacing, cell parameters, unit cell volume, lattice strain, and dislocation density were maximum for the Mn content of 0.2%. The acquired values of the optical band gap (Eg) are 3.39, 3.52, 3.58, and 3.18 eV for x = 0, 0.2%, 0.8%, and 1.2%, respectively. The corresponding absorption coefficient is reduced with increasing Mn content. The obtained refractive indices are 1.437, 1.402, 1.428, and 1.426 for x = 0, 0.2, 0.8, and 1.2%, respectively. The above results confirm that the MnxCo0.015Zn1-xO with x = 0.8% provides the lowest absorption and the highest value of bandgap. Thus, it can be the most suitable ETL for high-performance PSCs. The simulation results reveal that via applying MCZO ETL, the efficiency can be achieved over 23%.