Covalent Organic Framework Thin-Film Photodetectors from Solution-Processable Porous Nanospheres

Bag S, Sasmal HS, Chaudhary SP, Dey K, Blaette D, Guntermann R, Zhang Y, Poloz M, Kuc A, Shelke A, Vijayaraghavan RK, Ajithkumar TG, Bhattacharyya S, Heine T, Bein T, Banerjee R (2023)

Publication Type: Journal article

Publication year: 2023

Journal

Journal of the American Chemical Society American Chemical Society

Book Volume: 145

Pages Range: 1649-1659

Journal Issue: 3

DOI: 10.1021/jacs.2c09838

Abstract

The synthesis of homogeneous covalent organic framework (COF) thin films on a desired substrate with decent crystallinity, porosity, and uniform thickness has great potential for optoelectronic applications. We have used a solution-processable sphere transmutation process to synthesize 300 ± 20 nm uniform COF thin films on a 2 × 2 cm2 TiO2-coated fluorine-doped tin oxide (FTO) surface. This process controls the nucleation of COF crystallites and molecular morphology that helps the nanospheres to arrange periodically to form homogeneous COF thin films. We have synthesized four COF thin films (TpDPP, TpEtBt, TpTab, and TpTta) with different functional backbones. In a close agreement between the experiment and density functional theory, the TpEtBr COF film showed the lowest optical band gap (2.26 eV) and highest excited-state lifetime (8.52 ns) among all four COF films. Hence, the TpEtBr COF film can participate in efficient charge generation and separation. We constructed optoelectronic devices having a glass/FTO/TiO2/COF-film/Au architecture, which serves as a model system to study the optoelectronic charge transport properties of COF thin films under dark and illuminated conditions. Visible light with a calibrated intensity of 100 mW cm-2 was used for the excitation of COF thin films. All of the COF thin films exhibit significant photocurrent after illumination with visible light in comparison to the dark. Hence, all of the COF films behave as good photoactive substrates with minimal pinhole defects. The fabricated out-of-plane photodetector device based on the TpEtBr COF thin film exhibits high photocurrent density (2.65 ± 0.24 mA cm-2 at 0.5 V) and hole mobility (8.15 ± 0.64 ×10-3 cm2 V-1 S-1) compared to other as-synthesized films, indicating the best photoactive characteristics.

Involved external institutions

Indian Institute of Science Education and Research (IISER) Kolkata IN India (IN) Ludwig-Maximilians-Universität (LMU) DE Germany (DE) Technische Universität Dresden DE Germany (DE) National Chemical Laboratory (NCL) IN India (IN) Helmholtz-Zentrum Dresden-Rossendorf (HZDR) DE Germany (DE)

How to cite

APA:

Bag, S., Sasmal, H.S., Chaudhary, S.P., Dey, K., Blaette, D., Guntermann, R.,... Banerjee, R. (2023). Covalent Organic Framework Thin-Film Photodetectors from Solution-Processable Porous Nanospheres. Journal of the American Chemical Society, 145(3), 1649-1659. https://dx.doi.org/10.1021/jacs.2c09838

MLA:

Bag, Saikat, et al. "Covalent Organic Framework Thin-Film Photodetectors from Solution-Processable Porous Nanospheres." Journal of the American Chemical Society 145.3 (2023): 1649-1659.

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