Fine-Scale Aerosol-Jet\nPrinting of Luminescent Metal–Organic\nFramework Nanosheets

Fabrication of metal–organic framework (MOF) thin\nfilms\nis an ongoing challenge to achieve effective device integration. Inkjet\nprinting has been employed to print various luminescent metal–organic\nframework (MOF) films. Luminescent metal–organic nanosheets\n(LMONs), nanometer-thin particles of MOF materials with comparatively\nlarge micrometer lateral dimensions, provide an ideal morphology that\noffers enhancements over analogous MOFs in luminescent properties\nsuch as intensity and photoluminescent quantum yield. The morphology\nis also better suited to the formation of thin films. This work harnesses\nthe preferential features of LMONs to access the advanced technique\nof aerosol-jet printing (AJP) to print luminescent films with precise\ngeometries and patterns across the micrometer and centimeter length\nscales. AJP of LMONs exhibiting red (R), green (G), and blue (B) emission\nwere studied systematically to reveal the increase of luminescence\nupon additive layering printing until a threshold was reached limited\nby self-quenching. By combining different LMON emitters, emission\nchromaticity and intensity were shown to be tunable, including the\ncombination of RGB emitters to fabricate white-light-emitting films.\nA white-light LMON film was printed onto a UV light emitting diode\n(LED), producing a working white-light-emitting diode. Printing with\nmultiple distinct photoluminescent inks produced intricate multicolor\npatterns that dynamically responded to excitation wavelength, acting\neither as micrometer-scale LED-type cells or larger visual tags. Collectively,\nthe work offers an advancement for MOF thin films by printing MON\nmaterials using AJP, offering a precise method for manufacturing a\nwide range of critical functional devices, from luminescent sensors\nto optoelectronics, and more broadly even the opportunity for printed\ncircuitry with conductive MONs.