In recent years, Dr. Hong Sung-jun's team of the Photovoltaic Research Department of Korea Institute of Energy Research (KIER) has tremendous efforts have been employed in designing new perovskite materials and optimizing device architectures, which have boosted the power conversion efficiency (PCE) of perovskite solar cells (PSCs) from 3.8% to 25.7%.

Until now, the record PCE for single junction PSCs has been consistently achieved using a regular n-i-p device architecture with a stack of electron transport layer (ETL)/perovskite/hole transport layer (HTL), rather than with the inverted p-i-n counterparts.

We have recently reported the use of Br-2EPT (2-(3,7-dibromo-10H-phenothiazin-10-yl)ethyl)phosphonic acid) as a hole selective interlayer in highly efficient and stable inverted PSCs, and highlighted its advantages over commonly used polymeric HTLs such as PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl]amine).

Br-2EPT was found to be effective for controlling the interface energetics and non-radiative loss pathways, which are the most critical factors affecting PCE and stability of PSCs.

In addition, we found that these properties were greatly influenced by the head groups of the SAMs that directly contact the perovskite absorber.

Further fine-tuning of the SAMs’ head groups will provide more opportunities to enhance the photovoltaic properties of inverted PSCs toward a practically applicable technology.

The findings were published in the prestigious international journal ADVANCED FUNCTIONAL MATERIALS.

* https://onlinelibrary.wiley.com/doi/full/10.1002/adfm.202208793