Boosting the Optoelectronic Performance by Regulating Exciton Behaviors in a Porous Semiconductive Metal–Organic Framework

Abstract

Exciton behaviors including exciton formation and dissociation dynamics play an essential role in the optoelectronic performance of semiconductive materials but remain unexplored in semiconductive metal–organic frameworks (MOFs). Herein, we reveal that the exciton behaviors in semiconductive MOFs can be regulated by framework–guest interactions, a feature often not achievable in traditional inorganic or organic semiconductors. Incorporation of the electron-deficient molecule within the pores of a terbium-based semiconductive MOF (Tb2L2·4H2O·6DMF, L = TATAB3–, 4,4′,4″-s-triazine-1,3,5-triyltri-p-aminobenzoate, DMF = N,N-dimethylformamide) results in efficient energy transfer from the MOF skeleton to molecular acceptors, with a yield of up to 77.4%. This interaction facilitates distinctive exciton type conversion, giving rise to modified conductivity and photoelectric performance. We further fabricated a MOF-based X-ray detection device to demonstrate how the new architecture bolsters the optoelectronic efficiency, which outperforms the properties of parent semiconductive MOFs, with more than 60 times and 40 times enhancement of the photocurrent on–off ratio and detection sensitivity, respectively. With judiciously optimized exciton behaviors, the detection device exhibits a high sensitivity of 51.9 μC Gyair –1 cm–2 and records a charge carrier mobility-lifetime product of 1.12 × 10–3 cm2 V–1 among MOF-based X-ray detectors, which are competitive with values for commercially available detectors. These findings demonstrate a rational synthetic approach to designing exciton arrangements to improve the optoelectronic efficiency of semiconductive MOFs.

A novel 2D metal–organic framework probe: a highly sensitive and visual fluorescent sensor for Al3+, Cr3+ and Fe3+ ions

“…16 Metal-organic frameworks (MOFs) are outstanding candidates for fluorescence sensors because of their adjustable structures, modified ligands and active sites, high surface areas and tunable physicochemical properties. [17][18][19][20] In recent years, small molecules, ions, solvents, gases, biomolecules, pH, temperature and other types of analytes have been efficiently detected by MOF-based fluorescent sensors. [21][22][23][24][25][26][27][28] The detection mechanism based on MOFs is also attributed to the electron/ energy transfer, which is closely related to the weak interactions (p-p stacking or hydrogen bonds) between the MOFs and the analytes.…”

Connecting the Dots for Fundamental Understanding of Structure-Photophysics-Property Relationships of COFs, MOFs, and Perovskites using a Multiparticle Holstein Formalism

“…A recent study reported that the optoelectronic efficiency of semiconductive MOFs can be bolstered by efficient framework-guest interaction. 315 In particular, it was shown that the incorporation of electron-deficient guest molecules in the pores of a Terbium-based MOF results in significant energy transfer and facilitates the conversion of Wannier-type excitons into Frenkel-type excitons.…”

Charge Transport and Photoconductivity in a Hybrid Uranium(IV) Halide Perovskite

“…As shown in Figure 3A, under X-ray irradiation, the photocurrent sharply changes to the range of 10 −9 −10 −8 A with an increase of 2 orders of magnitude compared to the leakage current under dark conditions, suggesting a significant charge transport in EAUCl. 31 Note that the photocurrent of D2 is slightly lower than that of D1, which is attributed to thickness-induced charge carrier loss. We further monitored the radiation stability of EAUCl.…”