Two‐Dimensional Bis(dithiolene)iron(II) Self‐Powered UV Photodetectors with Ultrahigh Air Stability

Abstract

Organometallic two-dimensional (2D) nanosheets with tailorable components have recently fascinated the optoelectronic communities due to their solution-processable nature. However, the poor stability of organic molecules may hinder their practical application in photovoltaic devices. Instead of conventional organometallic 2D nanosheets with low weatherability, an air-stable -conjugated 2D bis(dithiolene)iron(II) (FeBHT) coordination nanosheet (CONASH) is synthesized via bottom-up liquid/liquid interfacial polymerization using benzenehexathiol (BHT) and iron(II) ammonium sulfate [Fe(NH 4 ) 2 (SO 4 ) 2 ] as precursors. The uncoordinated thiol groups in FeBHT are easily oxidized, but the Fe(NH 4 ) 2 (SO 4 ) 2 dissociation rate is slow, which facilitates the protection of sulfur groups by iron(II) ions. The density functional theory calculates that the resultant FeBHT network gains the oxygen-repelling function for oxidation suppression. In air, the FeBHT CONASH exhibits self-powered photoresponses with short response times (<40 ms) and a spectral responsivity of 6.57 mA W −1 , a specific detectivity of 3.13 × 10 11 Jones and an external quantum efficiency of 2.23% under 365 nm illumination. Interestingly, the FeBHT self-powered photodetector reveals extremely high long-term air stability, maintaining over 94% of its initial photocurrent after aging for 60 days without encapsulation. These results open the prospect of using organometallic 2D materials in commercialized optoelectronic fields.

From Theory to Experiment: Cascading of Thermocatalysis and Electrolysis in Oxygen Evolution Reactions

“…The optimized structure of the Fe-BHT monolayer is shown in Figure a. The unit cell of Fe-BHT monolayer consists of 3 Fe atoms with the optimized lattice constants being a = b = 8.55 Å, which is in good agreement with previous results. , In the Fe-BHT monolayer, each Fe atom is connected with four neighboring thiol-based organic ligands via Fe–S bonds (Figure b), forming a kagome lattice. , The thermal stability of this structure is investigated with ab initio molecular dynamics (AIMD) calculations with a time step of 1.0 fs for a total 10 ps. As shown in Figure S1, no obvious structural distortion or deformation of the Fe-BHT monolayer was observed after 10 000 steps at 298.15 K, indicating good thermal stability under ambient conditions.…”

“…The unit cell of Fe-BHT monolayer consists of 3 Fe atoms with the optimized lattice constants being a = b = 8.55 Å, which is in good agreement with previous results. 44,45 In the Fe-BHT monolayer, each Fe atom is connected with four neighboring thiol-based organic ligands via Fe−S bonds (Figure 1b), forming a kagome lattice. 46,47 The thermal stability of this structure is investigated with ab initio molecular dynamics (AIMD) calculations with a time step of 1.0 fs for a total 10 ps.…”

“…The prominent diffraction peaks for Fe-BHT in the XRD pattern (Figure S7) are in good agreement with literature. 44,45 The electrocatalytic activity of Fe-BHT toward OER was evaluated using a standard three-electrode cell in 1.0 M N 2 -saturated KOH electrolyte (pH 14) at a scan rate of 5 mV s −1 . The linear sweep voltammetry (LSV) curves of Fe-BHT at different temperatures are shown in Figure 4b.…”

Terpyridine-zinc(ii) coordination nanosheets as modulators of perovskite crystallization to enhance solar cell efficiency

“…Recently, beneting from the conductivity and material variability of CONASHs, we synthesized a UVsensitized bis(dithiolene)iron(II) complex motif by combining benzenehexathiol (BHT) ligands and iron(II) ions to fabricate a self-powered photodetector, which exhibited a spectral responsivity of 6.57 mA W −1 under 365 nm light radiation. 13 Additionally, once the size of the ligands increases, more CONASHs with different structures and photofunctions can be designed because of the customized steric hindrance. For example, aer replacing the small-sized BHT with a largemolecule three-way terpyridine (TPY), the extended molecular space between TPYs allowed accommodating larger ZnSO 4 molecules.…”

A self-powered flexible UV-visible photodetector with high photosensitivity based on BiFeO3/XTiO3 (Sr, Zn, Pb) multilayer films

“…1–5 Traditional photodetectors rely on an external power supply to realize their optical detection behavior, and the external field generally leads to high dark current and small switching ratio, limiting their practical application. 6–8 Nowadays, self-powered photodetectors have attracted extensive attention due to their long-term self-powered detection, low energy consumption and easy integration with small functional devices. 9–14 Self-powered photodetectors are usually constructed using a p–n junction, or Schottky junction; however, their applications are limited due to their limited photoelectric conversion efficiency and theoretical photovoltage value.…”