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Chinese researchers have manufactured a carbon-based perovskite solar cell that achieves almost the same efficiency as its gold electrode-based perovskite counterparts, while offering greater stability. The novel devices use a plasticine-like graphite (PG) electrode that combines the deformable property of carbon paste and the solvent-free property of carbon film.
A group of researchers led by Wuhan University of Technology has manufactured a carbon-based perovskite solar cell that uses plasticine-like graphite putty (PG) as an electrode.
“The plasticine-like carbon electrode is the latest and best carbon electrode technique available in our laboratory,” Junyan Xiao, lead author of the research, told pv magazine . “Superior electrodes can be realized with this comfortable, efficient and damage-free contact between the functional layers.”
The research group explained that PG exhibits the deformable property of carbon paste and the solvent-free property of carbon film, both used in previous research on carbon-based perovskite cells, and noted that carbon electrodes offer almost the same efficiency as gold (Au) electrodes, while providing greater stability.
The scientists designed the cell with a fluorine-doped tin oxide (FTO) substrate, an electron transport layer (ETL) based on yttrium-doped tin oxide (SnO2), a perovskite absorber, a gaps (HTL) based on Spiro-OMeTAD and the PG electrode. “PG sheets of appropriate size were placed on the FTO/SnO2/perovskite/spiro-OMeTAD semi-device by roller pressing or plate-to-plate lamination pressing (1 MPa) at room temperature,” they stressed.
Using this architecture, the group built a cell with an active surface area of ??0.15 cm2. Tested under standard conditions, this device achieved a power conversion efficiency of 20.29%, an open circuit voltage of 1.13 V, a short circuit current of 22.29 mA-cm-2 and a fill factor of 81%. For comparison, a reference cell with an Au metal contact achieved an efficiency of 21.04%, an open circuit voltage of 1.13 V, a short circuit current of 22.27 mA-cm-2 and a fill factor of 81%.
However, the efficiency of the Au electrode cell decreased below 40% over 300 h, while the PG electrode cell was able to retain 96.3% of the initial efficiency after 1,300 h. “It is believed that the drying-hygroscopic dynamic equilibrium of sorbitol can prevent moisture penetration into the perovskite layer, and help form a better HTL/PG interface during long-term storage,” the academics explained. “In addition, the PG-L electrode has good mechanical stability in the device and can easily withstand the tape test under a tensile force of 5 N.”
Using the novel carbon-based cell, the group fabricated a perovskite solar module on 5 cm × 5 cm FTO substrates. To build the monolithic interconnections that add voltages between the cells of the modules, laser tracing P1, P2 and P3 was used. The panel achieved an efficiency of 16.01%, an open circuit voltage of 6.58 V, a short circuit current of 3.65 mA-cm-2 and a fill factor of 67%, a performance that was described as “quite outstanding.”
“The PG material and its processing method integrate the advantages of the printable electrode made from low-temperature carbon paste and the transfer electrode made from prefabricated carbon film,” the researchers concluded. “Despite the shortcomings of the PG electrode in terms of optical reflection and module conductivity in relation to the Au electrode, the low cost of the material, environmental sustainability, simplicity of the process and easy scalability of the PG electrode make this technique is very promising for the industrialization of carbon-based perovskite solar cells.”
The novel perovskite solar cell and module concept was described in the study “ Playdough-like carbon electrode: A promising strategy for high efficiency perovskite solar cells and modules ” high-efficiency perovskite), published in eScience . |
