A research team led by Prof. GE Ziyi from the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences, in collaboration with Prof. QU Bo from Peking University, has developed a novel passivator soluble in low-polarity solvents, achieving a stable perovskite solar cell (PSC) with a power conversion efficiency (PCE) of up to 26.07%.
The findings were recently published in Advanced Materials.
PSCs have emerged as a promising third-generation photovoltaic technology due to their low fabrication costs and high PCEs. While various passivators, such as ammonium salts and Lewis acids, are known to enhance PSC performance by reducing interfacial defects and suppressing non-radiative recombination, most conventional options face a critical limitation: they require high-polarity solvents, which often introduce additional defects on the perovskite surface. This issue ultimately compromises device stability and leads to poor reproducibility.
To address this challenge, the researchers synthesized a bisphosphate-based molecular passivator (named DCTP) that simultaneously solves solvent compatibility issues, strengthens defect passivation, and improves hole extraction. An advantage of DCTP is its solubility in low-polarity solvents, including toluene, chlorobenzene, and chloroform, without damaging the perovskite surface.
When the researchers applied DCTP as an intermediate layer via chlorobenzene processing, they found it delivers multiple benefits. It effectively passivates surface defects, optimizes energy level alignment at the perovskite/hole transport layer interface, and suppresses the interlayer diffusion of formamide (FA+), iodide (I-), and lithium (Li+) ions under thermal stress.
The researchers noted that a "champion" DCTP-treated PSC with a PCE of 26.07% is a new record for perovskite solar cells using passivators processed with non-polar solvents. Additionally, under the ISOS-D-2I protocol, the device retained over 90.1% of its initial PCE after 900 hours at 65 °C.
This work unlocks a novel multifunctional passivator design that dissolves in low-polarity solvents, paving the way for high-performance and scalable photovoltaics.
DCTP's solubility in low-polarity solvents without surface damage versus conventional passivators. (Image by NIMTE)
