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Chinese researchers have built one of the most efficient carbon-electrode perovskite solar cells on record.
Researchers at Henan University in China have manufactured a perovskite solar cell based on a carbon electrode that achieves a power conversion efficiency of 20.8% and offers greater stability.
The metallic contact electrodes that are commonly used today can stimulate the degradation of perovskite solar cells due to the diffusion of metallic impurities across the interfaces. This problem could theoretically be overcome by replacing the metal contact with carbon electrodes, which hold great promise for commercialization due to their ambient pressure processability based on industrially established printing techniques.
However, perovskite solar cells based on carbon electrodes pose a problem in other parts of the devices, as they cause performance losses at the point where the carbon electrode meets the perovskite layer.
“In perovskite solar cells with carbon electrodes, the interfacial contact between the carbon electrode and the perovskite is of great importance for the performance of the solar cells,” the scientists state. “Most inorganic hole transport layers (HTLs) are based on dispersive nanoparticles that could easily aggregate and form rough contact with both perovskite and viscous carbon paste; the capture of gaps is thus negatively affected”.
They tried to solve this problem by placing an organic semiconducting polymer called polythiophene (P3HT) between perovskite and an HTL made of nickel(II) oxide (NiOx) and claimed that this organic/inorganic planar HTL structure has superior electrical contact for cells. perovskite solar cells with carbon electrode.
“The organic layer of P3HT allows for effective moisture habituation and a densely contacted interface with a matching energy level alignment with the perovskite, while the stable layer of NiOx nanoparticles further protects the P3HT from paste corrosion. so that we can further optimize the deposition of the carbon sheet coating to form a dense contact with the HTL,” they also explained.
The Chinese group built the cell with an indium tin oxide (ITO) substrate, a tin oxide (SnO2) buffer layer, a perovskite absorber, the P3HT layer, the NiOx HTL, and a carbon electrode.
The electrode is based on a carbon paste containing carbon black and powdered graphite supplied by Saidi Technology Development Inc. of China. “The carbon electrode was prepared by a knife coating process and the wet film was annealed at 110ºC for 5 minutes,” it says.
The academics compared the performance of the solar cell with that of a reference device without the modified anode buffer interfaces, which they say are capable of facilitating charge collection.
The champion solar cell built with these interfaces achieved a power conversion efficiency of 20.8%, an open circuit voltage of 1.15 eV, a short circuit current of 22.9 mA/cm2, and a fill factor of 78 .8%
“This efficiency is among the highest values ??for carbon-electrode perovskite solar cells; a champion efficiency of 22% was reported from half-cell assembly with carbon electrode substrate,” they stated. "The operational stability of this cell is obviously improved by the introduction of the hydrophobic layer of P3HT and the dense carbon precoat."
The reference device, by contrast, achieved an efficiency of only 13.4%. |
