Alkylammonium bis(trifluoromethylsulfonyl)imide as a dopant in the hole-transporting layer for efficient and stable perovskite solar cells

Abstract

In state-of-the-art n-i-p structured perovskite solar cells (PSCs), a dopant for doping hole transporting materials (HTMs) is a crucial component, which not only affects the electrical property of HTMs, but...

Archetype-Cation-Based Room-Temperature Ionic Liquid: Aliphatic Primary Ammonium Bis(trifluoromethylsulfonyl)imide as a Highly Functional Additive for a Hole Transport Material in Perovskite Solar Cells

“…In conclusion, n -octylammonium bis­(trifluoromethylsulfonyl)­imide (OA-TFSI), which comprises an archetypal cation and a modern anion, is designed for use as an additive for HTMs in PSCs, which we proposed before the recent publication using PTAA HTM. OA-TFSI was successfully synthesized and exhibited prominent and multiple functions in PSCs based on Spiro-OMeTAD HTM simultaneously: (i) spontaneous and dense perovskite passivation by the OA cations and (ii) effective stabilization and generation of the Spiro-OMeTAD HTM cationic radicals by the TFSI anions, improving hole collection (Figure b).…”

“…Very recently, OA-TFSI addition to another HTM (i.e., poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]: PTAA) was reported . However, using the most common Spiro-OMeTAD HTM to demonstrate the concept proposed herein, which was reported by us before the publication regarding PTAA, is of interest, and further understanding of the function of OA-TFSI is desirable. In the present work, OA-TFSI exhibited multiple simultaneous functions: effective stabilization of the Spiro-OMeTAD radical by the TFSI anions in the absence of counter cations, suppression of defects at the Spiro-OMeTAD/perovskite interface, and rendering the perovskite surface hydrophobic (Figure b).…”

“…To demonstrate the proposed concept, in this study, an RTIL comprising the archetypal aliphatic primary ammonium cations (i.e., n -octylammonium (OA)) and modern TFSI anions (OA-TFSI, , Figure a, right) was synthesized and used as an additive in a Spiro-OMeTAD HTM. Very recently, OA-TFSI addition to another HTM (i.e., poly­[bis­(4-phenyl)­(2,4,6-trimethylphenyl)­amine]: PTAA) was reported .…”

“…To demonstrate the proposed concept, in this study, an RTIL comprising the archetypal aliphatic primary ammonium cations (i.e., n -octylammonium (OA)) and modern TFSI anions (OA-TFSI, , Figure a, right) was synthesized and used as an additive in a Spiro-OMeTAD HTM. Very recently, OA-TFSI addition to another HTM (i.e., poly­[bis­(4-phenyl)­(2,4,6-trimethylphenyl)­amine]: PTAA) was reported . However, using the most common Spiro-OMeTAD HTM to demonstrate the concept proposed herein, which was reported by us before the publication regarding PTAA, is of interest, and further understanding of the function of OA-TFSI is desirable.…”

In situ dipole formation to achieve high open-circuit voltage in inverted perovskite solar cells via fluorinated pseudohalide engineering

“…Therefore, it is urgent to develop an in situ passivation technology to regulate the energy levels near the top surface in p–i–n PSCs. 18,19…”