Abstract
Inorganic hole-transporting materials (HTMs) for stable and cheap inverted perovskite-based solar cells are highly desired. In this context, NiOx, with low synthesis temperature, has been employed. However, the low conductivity and the large number of defects limit the boost of the efficiency. An approach to improve the conductivity is metal doping. In this work, we have synthesized cobalt-doped NiOx nanoparticles containing 0.75, 1, 1.25, 2.5, and 5 mol% cobalt (Co) ions to be used for the inverted planar perovskite solar cells. The best efficiency of the devices utilizing the low temperature-deposited Co-doped NiOx HTM obtained a champion photoconversion efficiency of 16.42%, with 0.75 mol% of doping. Interestingly, we demonstrated that the improvement is not from an increase of the conductivity of the NiOx film, but due to the improvement of the perovskite layer morphology. We observe that the Co-doping raises the interfacial recombination of the device but more importantly improves the perovskite morphology, enlarging grain size and reducing the density of bulk defects and the bulk recombination. In the case of 0.75 mol% of doping, the beneficial effects do not just compensate for the deleterious one but increase performance further. Therefore, 0.75 mol% Co doping results in a significant improvement in the performance of NiOx-based inverted planar perovskite solar cells, and represents a good compromise to synthesize, and deposit, the inorganic material at low temperature, without losing the performance, due to the strong impact on the structural properties of the perovskite. This work highlights the importance of the interface from two different points of view, electrical and structural, recognizing the role of a low doping Co concentration, as a key to improve the inverted perovskite-based solar cells’ performance.
Highlights
Organic-inorganic halide perovskite solar cells (PSCs) have gained increasing attention owing to their high power conversion efficiencies and fabrication in solution at low temperatures
The NiOx has been formed with relatively high phase purity and, according to the difference in the peaks intensities between the samples of undoped NiOx and Co-doped NiOx, it is clear that Ni ions have been successfully replaced
The NiOx has been formed with relatively high phase purity and, according to the difference in the peaks intensities between the samples of undoped NiOx and Co-doped NiOx, it is clear that Ni ions have been successfully replaced with Co ions, as demonstrated by energy-dispersive X-ray spectroscopy (EDS) measurements (Figure S1) [40]
Summary
Organic-inorganic halide perovskite solar cells (PSCs) have gained increasing attention owing to their high power conversion efficiencies and fabrication in solution at low temperatures. The two most common architecture used in the fabrication of PSCs are the n-i-p and p-i-n configurations and the current highest efficiencies are achieved with the n-i-p one, using TiO2 as ETM and doped Spiro-OMeTAD as HTM [4]. This configuration is characterized by the high cost of the HTM and by a slight hysteresis, which has to be avoided with the use of special treatment or interlayers [5].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
