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A group of Korean scientists has employed a hot air technique instead of atomic layer deposition to fabricate a perovskite absorber that reportedly presents a higher quality film. They applied this film in a tandem perovskite-organic solar cell, which showed low open-circuit voltage losses and high levels of efficiency.
Researchers at Chonnam National University (South Korea) have designed a two-terminal organic perovskite monolithic tandem solar cell based on a metal ion-doped perovskite absorber and a “nip” arrangement.
In the nip or “inverted” architecture, the solar cell is illuminated through the electron transport layer (ETL) side; in the pin structure, it illuminates through the surface of the hole transport layer (HTL).
“We have demonstrated a new hot air method for tandem monolithic solar cells and their stabilization by doping with metal ions,” lead author Sawanta S. Mali told pv magazine , adding that the proposed manufacturing process It lacks the atomic layer deposition (ALD) and sputtering techniques commonly used for deposition of a protective interconnect layer on tandem devices. “Except for thermally evaporated molybdenum trioxide (MoO3) and silver (Ag), all layers were fabricated under ambient air conditions.”
Unlike the conventional antisolvent method, the hot air technique supposedly facilitates the formation of a highly uniform intermediate complex due to partial evaporation of the solvent, resulting in a higher quality perovksite film. “We blew a hot air gun at 150°C directly onto the spun substrate,” the scientists explained.
The top perovskite cell was constructed with a fluorine-doped tin oxide (FTO) substrate, a mesoscopic electron transfer layer (ETL), the perovskite absorber, a 3-based hole transport layer (HTL), 4,9,10-tetra(n-alkoxycarbonyl)-perylenes (PTAC), a premium donor material known as PBDB-T, a molybdenum trioxide (MoO3) buffer layer, and a silver (Ag) metal contact.
The bottom organic cell was fabricated with an ITO and glass based substrate, a window layer of zinc oxide (i-ZnO) and PDI derivative (PDIN), a layer of phenyl-C61-butyric acid methyl ester (PCBM) , a MoO3 buffer layer and an Ag metal contact.
Tested under standard lighting conditions, the champion tandem device built with this architecture achieved a power conversion efficiency of 23.07%, an open circuit voltage of 2.110 V, a short circuit current density of 13.65 mAcm. 2 and a fill factor of 80.1%.
The device was also able to retain more than 90% of initial efficiency for 600 h at full power under continuous illumination.
“Our method demonstrates that solution-processed absorbers with organic cation passivation reduce open-circuit voltage loss to 0.025 V, the lowest recorded to date,” the scientists stated. “This structure also demonstrates the advantages of limited recombination and high reproducibility.”
The novel cell design was presented in the article “ All-inorganic halide perovskites for air-processed ni-p monolithic perovskite/organic hybrid tandem solar cells exceeding 23% efficiency ” air-processed ni-p monolithic organic/perovskite hybrids exceeding 23% efficiency), published in Energy & Environmental Science . |
