RESUMEN
Sputtered NiO x (sp-NiO x ) is a preferred hole transporting material for perovskite solar cells because of its hole mobility, ease of manufacturability, good stability, and suitable Fermi level for hole extraction. However, uncontrolled defects in sp-NiO x can limit the efficiency of solar cells fabricated with this hole transporting layer. An interfacial layer has been proposed to modify the sp-NiO x /perovskite interface, which can contribute to improving the crystallinity of the perovskite film. Herein, a 2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz) self-assembled monolayer was used to modify an sp-NiO x surface. We found that the MeO-2PACz interlayer improves the quality of the perovskite film due to an enlarged domain size, reduced charge recombination at the sp-NiO x /perovskite interface, and passivation of the defects in sp-NiO x surfaces. In addition, the band tail states are also reduced, as indicated by photothermal deflection spectroscopy, which thus indicates a reduction in defect levels. The overall outcome is an improvement in the device efficiency from 11.9% to 17.2% due to the modified sp-NiO x /perovskite interface, with an active area of 1 cm2 (certified efficiency of 16.25%). On the basis of these results, the interfacial engineering of the electronic properties of sp-NiO x /MeO-2PACz/perovskite is discussed in relation to the improved device performance.
RESUMEN
Reduced graphene oxide (rGO) is generated from GO dispersed in water under continuous flow in the absence of harsh reducing agents, in a vortex fluidic device, such that the processing is scalable with uniformity of the product. This involves simultaneously UV irradiating (λ = 254 nm, 20 W) the dynamic thin film in the rapidly rotating glass tube in the microfluidic platform. The rGO is comparable to that formed using waste generating chemical based processing, with a film of the material having a resistance of 2.2 × 105 Ω and a remarkably high conductivity of 2 × 104 S cm-1.
