Researchers in Taiwan have developed an efficient approach for carrier transport and defect passivation at the nickel oxide/perovskite interface in perovskite solar cells, enabling devices with efficiencies of 42% under indoor lighting conditions, and more than 20% under simulated sunlight .
Recent advances in the development of perovskite solar cells for indoor applications have resulted in indoor energy conversion efficiency of more than 40%, driven by improvements in both bulk and passivation of interfacial defects, 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 through the use of self-assembled monolayers (SAMs), which reportedly improve perovskite growth and optoelectronic properties. The study’s lead author, Chih-Ping Chen, said pv magazine that the cell achieved an indoor energy conversion efficiency of 42% under 3,000 K LED lighting at 1,000 lux.
“This breakthrough highlights the potential of our approach to further develop indoor perovskite solar cell (PSC) technologies, expanding their applicability in low-light environments,” said Chen. “We specifically focused on the passivation effects of four commonly used SAMs for the modification of nickel(II) oxide (NiOx) in inverted perovskite solar cells, where MeO-2PACz and 4PADCB appear to be particularly effective in modifying the hole-selective layer ( HSL), optimizing surface properties and improving energy level alignment.”
In particular, the research team investigated the effect of four SAMs with different linker lengths and terminal functional groups on critical NiOx/perovskite interfacial films, depositing them via spin-coating. The SAMs used were 2PACz, MeO-2PACz, 4PADCB and Me-4PACz.
The researchers analyzed the performance of the perovskite cells made with SAM-modified NiOx layers and wide bandgap perovskite layers based on Cs0.18FA0.82Pb(I0.8Br0.2)3, finding that they achieved an “impressive performance.” of more than 20%. energy conversion efficiency 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 efficiencies of 20.19% and 20.18%, respectively. This contrasts with the best performing reference cell which had an efficiency of 14.98%. They also noted improved open-circuit voltage and fill factor values for the target devices.
The target devices showed a “remarkable improvement” compared to the control device, which the researchers attributed to reduced non-radiative recombination and better carrier motion, indicating a reduction in defect density at the HSL/perovskite interface.
The cells are made with a substrate made of indium tin oxide (ITO), the NiOX film, SAMs, a perovskite absorber, an electron transport layer based on phenyl-C61-butyric acid methyl ester (PCBM), a bathocuproin (BCP) buffer layer and a silver (Ag) metal contact.
“Our strategy not only significantly improves fill factor values but also paves the way for NiOx-based PSCs for indoor light harvesting applications,” the researchers concluded.
The new cell architecture was described in “Achieving indoor efficiency above 42% in wide bandgap perovskite solar cells through optimized interfacial passivation and carrier transport”, which was recently published in Journal of Chemical Technology.
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