# Stacking Effects on the Optoelectronic Properties of 2D Perylene-Zn-Porphyrin-Based COFs

## TL;DR

This study explores how stacking layers in a 2D COF material affects its electronic and optical properties, showing that controlled stacking can improve performance in optoelectronic devices.

## Contribution

The work demonstrates that controlled layer stacking in COFs can be used to tailor electronic and optical properties through AA stacking effects.

## Key findings

- AA stacking modifies the geometry and electronic structure of perylene–Zn–porphyrin COFs.
- Transition to planar multilayered frameworks reduces band gaps and shifts absorption dominance to porphyrin units.
- Stacking influences frontier orbital delocalization and enables tunable optoelectronic properties.

## Abstract

Crystalline porous materials, such as covalent organic
frameworks
(COFs), have emerged as promising candidates for photocatalytic and
optoelectronic applications due to their tunable architecture and
capacity to mitigate charge recombination. The incorporation of highly
aromatic organic building blocks that promote self-assembly and columnar
growth enables the formation of COFs with a controlled layer thickness.
However, the influence of interlayer stacking on the structural and
optoelectronic behaviors of these materials remains poorly understood.
In this work, we combine experimental and theoretical approaches to
elucidate the stacking-induced evolution of perylene–Zn–porphyrin
COFs. Spectroscopic and microscopic analyses, supported by density
functional theory (DFT) calculations, reveal that self-assembly through
AA stacking markedly modifies both the geometry and electronic structure.
The transition from nonplanar 2D architectures to planar multilayered
frameworks results in reduced band gaps, inversion of the frontier
crystalline orbital delocalization, and a shift of absorption dominance
toward the porphyrin units. These findings demonstrate that controlled
layer stacking is a viable strategy to tailor the electronic and optical
properties of stacked 2D COFs, paving the way for their integration
into high-performance optoelectronic devices.