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Researchers in Taiwan have developed an efficient method for carrier transport and defect passivation at the nickel oxide/perovskite interface of perovskite solar cells, enabling devices with efficiencies of 42% under indoor lighting conditions and over 20% under simulated sunlight.
Recent advances in the development of perovskite solar cells for indoor applications have resulted in indoor power conversion efficiencies exceeding 40%, driven by improvements in both bulk and interfacial defect passivation, according to a research team led by Taiwan’s Ming Chi University of Technology.
With this in mind, the group sought to further optimize this cell technology by using self-assembled monolayers (SAMs), which are said to improve perovskite growth and optoelectronic properties. Lead author of the research, Chih-Ping Chen, told pv magazine that the cell achieved 42% power conversion efficiency indoors under 3,000 K LED lighting at 1,000 lux.
“This breakthrough highlights the potential of our method to further advance indoor perovskite solar cell (PSC) technologies by expanding their applicability in low-light environments,” Chen said. “We specifically focused on the passivation effects of four widely used SAMs for nickel(II) oxide (NiOx) modification in inverted perovskite solar cells, with MeO-2PACz and 4PADCB emerging as particularly effective in modifying the selective hole layer (HSL), optimizing surface properties, and improving energy level alignment.”
The team of researchers studied in particular the effect of four SAMs with different bond lengths and terminal functional groups on critical NiOx/perovskite films, which they deposited by spin coating. The SAMs applied were 2PACz, MeO-2PACz, 4PADCB and Me-4PACz.
The researchers analyzed the performance of perovskite cells fabricated with SAM-modified NiOx layers and broad band gap perovskite layers based on Cs0.18FA0.82Pb(I0.8Br0.2)3, and found that they achieved “impressive performance” exceeding 20% ??power conversion efficiencies under simulated sunlight at an intensity of AM 1.5 G 100 mW/cm2.
They also found that the best performing MeO-2PACz and 4PADCB devices had an efficiency of 20.19% and 20.18%, respectively. This is in contrast to the best performance of the reference cell, which had an efficiency of 14.98%. They also observed improved open circuit voltage and fill factor values ??of the target devices.
The target devices showed a “remarkable improvement” compared to the control device, which the researchers attributed to reduced nonradiative recombination and improved carrier motion, suggesting a reduction in defect density at the HSL/perovskite interface.
The cells were fabricated with an indium tin oxide (ITO) substrate, NiOx film, SAMs, a perovskite absorber, a phenyl-C61-butyric acid methyl ester (PCBM)-based electron transport layer, a bathocuproine (BCP) buffer layer, and a silver (Ag) metal contact.
“Our strategy not only significantly improves the fill factor values ??but also paves the way for NiOx-based PSCs for indoor light harvesting applications,” the researchers concluded.
The novel cell architecture is described in “ Achieving over 42 % indoor efficiency in wide-bandgap perovskite solar cells through optimized interfacial passivation and carrier transport,” recently published in the Chemical Engineering Journal . |
