# Interfacial Coupling Design Enhancing Hole Transport in PTAA-Based Perovskite Solar Cells with Efficiency over 26%

## TL;DR

Researchers designed new ligands to improve hole transport in perovskite solar cells, achieving a record efficiency of 26.13%.

## Contribution

A novel π-conjugation extension strategy using TPA-based ligands to enhance interfacial coupling in perovskite solar cells.

## Key findings

- P-TPEAI ligands achieved a record 26.13% efficiency in 2D/3D perovskite solar cells.
- The π-conjugation extension improved intermolecular interactions at perovskite/PTAA interfaces.
- The devices showed excellent light-heat stability meeting ISOS-L-2 protocol.

## Abstract

Two triphenylamine-based semiconducting ligands, namely N-TPEAI and P-TPEAI, were designed by extending the π-conjugation, with structural similarities to the backbone of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA).This π-conjugation extension strategy proves to be effective in strengthening intermolecular interactions both between adjacent spacer cations within 2D perovskites and at perovskite/PTAA interfaces.The resultant 2D/3D perovskite solar cells (PSCs) employing P-TPEAI achieve an outstanding efficiency of 26.13%, which is the highest value reported for 2D/3D PSCs incorporating PTAA hole-transport layers.

Two triphenylamine-based semiconducting ligands, namely N-TPEAI and P-TPEAI, were designed by extending the π-conjugation, with structural similarities to the backbone of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA).

This π-conjugation extension strategy proves to be effective in strengthening intermolecular interactions both between adjacent spacer cations within 2D perovskites and at perovskite/PTAA interfaces.

The resultant 2D/3D perovskite solar cells (PSCs) employing P-TPEAI achieve an outstanding efficiency of 26.13%, which is the highest value reported for 2D/3D PSCs incorporating PTAA hole-transport layers.

The online version contains supplementary material available at 10.1007/s40820-026-02145-4.

Constructing 2D/3D perovskite heterojunction is an effective method to improve performance and stability of perovskite solar cells (PSCs), while the quantum well in 2D perovskites hinders carrier transport. To address this issue, π-conjugated semiconducting ligands have been introduced to enhance carrier-transfer capability of 2D perovskites. Here, two triphenylamine (TPA)-based ligands are specifically designed through π-extension with a fused (N-TPEAI) or covalently linked (P-TPEAI) benzene ring. For the first time, TPA semiconductor-based ligands have been incorporated to construct 2D/3D PSCs with poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) as hole-transport materials (HTMs). Combined experimental and computational analyses reveal that this π-conjugation extension strategy proves to be effective in strengthening intermolecular interactions both between the adjacent spacer cations within 2D perovskites and at perovskite/PTAA interfaces, particularly in the case of P-TPEAI. Ultimately, the resultant 2D/3D PSCs employing P-TPEAI achieve an outstanding efficiency of 26.13%, which, to the best of our knowledge, is the highest value reported for 2D/3D PSCs incorporating PTAA HTMs. Moreover, benefiting from the robustness of both 2D perovskites and PTAA, the corresponding devices also exhibit excellent light-heat stability, meeting ISOS-L-2 protocol. These findings provide important guidelines for future design of organic spacers in advancing efficient and robust PSCs and related optoelectronic devices.

The online version contains supplementary material available at 10.1007/s40820-026-02145-4.