A synergistic effect of the ion beam sputtered NiO x hole transport layer and MXene doping on inverted perovskite solar cells

• Published in: Nanotechnology Vol. 33; no. 42; pp. 425202 - 425208
• Main Authors: Din, Muhammad Faraz Ud, Held, Vladimir, Ullah, Sami, Sousani, Shima, Omastova, Maria, Nadazdy, Vojtech, Shaji, Ashin, Siffalovic, Peter, Jergel, Matej, Majkova, Eva
• Format: Journal Article
• Language: English
• Published: IOP Publishing 15.10.2022
• Subjects: hole transport layer; ion beam sputtering; MXene; NiO; perovskite solar cells; power conversion efficiency
• ISSN: 0957-4484; 1361-6528
• DOI: 10.1088/1361-6528/ac7ed4

Abstract The synergistic effect of high-quality NiO x hole transport layers (HTLs) deposited by ion beam sputtering on ITO substrates and the Ti 3 C 2 T x MXene doping of CH 3 NH 3 PbI 3 (MAPI) perovskite layers is investigated in order to improve the power conversion efficiency (PCE) of p-i-n perovskite solar cells (PSCs). The 18 nm thick NiO x layers are pinhole-free and exhibit large-scale homogeneous surface morphology as revealed by the atomic force microscopy (AFM). The grazing-incidence x-ray diffraction showed a 0.75% expansion of the face-centered cubic lattice, suggesting an excess of oxygen as is typical for non-stoichiometric NiO x . The HTLs were used to fabricate the PSCs with MXene-doped MAPI layers. A PSC with undoped MAPI layer served as a control. The size of MAPI polycrystalline grains increased from 430 ± 80 nm to 620 ± 190 nm on the doping, as revealed by AFM. The 0.15 wt% MXene doping showed a 14.3% enhancement in PCE as compared to the PSC with undoped MAPI. The energy-resolved electrochemical impedance spectroscopy revealed one order of magnitude higher density of defect states in the band gap of MXene-doped MAPI layer, which eliminated beneficial effect of reduced total area of larger MAPI grain boundaries, decreasing short-circuit current. The PCE improvement is attributed to a decrease of the work function from −5.26 eV to −5.32 eV on the MXene doping, which increased open-circuit voltage and fill factor.