Molecular Engineering of Enamine‐Based Hole‐Transporting Materials for High‐Performing Perovskite Solar Cells: Influence of the Central Heteroatom

Abstract

Stabilizing the high-performing perovskite solar cells (PSCs) with low-cost and simply affordable hole-transporting materials (HTMs) has been identified as an ongoing ambitious challenge. Herein, a series of enamine-based HTMs having different central heteroatoms (C, N, O, and S) and a number of enamine branches is designed and synthesized. The impact of varied central heteroatom cores is investigated in-depth including thermal, photophysical, and photovoltaic properties. Importantly, molecularly engineered HTMs are obtained by a single condensation reaction without the need for expensive catalysts, inert reaction conditions, or tedious product purification. PSCs with a power conversion efficiency (PCE) of over 20% can be realized with the triphenylamine core HTM (V1435), a result comparable with spiro-OMeTAD. HTMs based on tetraphenylmethane (V1431) and diphenyl sulfide (V1434) cores give a slightly lower performance under similar device fabrication conditions. This work demonstrates how rational molecular engineering of a simple condensation approach can produce HTMs for high-performing PSCs without sacrificing the PCE.

A Multifunctional Dye Molecule as the Interfacial Layer for Perovskite Solar Cells

“…As displayed in Figure S5, building upon the B3LYP/6-H-BS1G* level, time-dependent density functional theory (TDDFT) calculations enable us to examine further aspects of ThPCyAc, including geometry conformations, frontier orbital distributions, and static electrostatic potential maps. A distorted spatial configuration in ThPCyAc molecule indirectly benefits denser intermolecular attachments, intensified interactions, and comparatively even distribution on the surface of perovskite films. − Overall, this structure discourages excessive molecular congregation. Beyond that, the main contribution shaping the molecule’s LUMO energy level stems from the acceptor part.…”

D-π-A-Type Pyrazolo[1,5-a]pyrimidine-Based Hole-Transporting Materials for Perovskite Solar Cells: Effect of the Functionalization Position

“…The second heating DSC curves are given in Figure S6. The results indicate that the three compounds have a stable amorphous morphology, with a high glass transition temperature (Tg) > 120 °C, which is beneficial for improving device stability [14,65]. While PY1 exhibits a lower Tg of 127 °C, similar to that Regarding the thermal properties of the HTMs, the molecular glass behavior and high thermal stability of the materials are favorable for obtaining suitable organic films [63].…”

“…The second heating DSC curves are given in Figure S6. The results indicate that the three compounds have a stable amorphous morphology, with a high glass transition temperature (T g ) > 120 • C, which is beneficial for improving device stability [14,65]. While PY1 exhibits a lower T g of 127 • C, similar to that of Spiro-OMeTAD (126 • C) [64], PY2 and PY3 demonstrate slightly higher T g at 136 • C and 135 • C, respectively.…”