Controlling the fluorescence and room-temperature phosphorescence behaviour of carbon nanodots with inorganic crystalline nanocomposites

Abstract

There is a significant drive to identify alternative materials that exhibit room temperature phosphorescence for technologies including bio-imaging, photodynamic therapy and organic light-emitting diodes. Ideally, these materials should be non-toxic and cheap, and it will be possible to control their photoluminescent properties. This was achieved here by embedding carbon nanodots within crystalline particles of alkaline earth carbonates, sulphates and oxalates. The resultant nanocomposites are luminescent and exhibit a bright, sub-second lifetime afterglow. Importantly, the excited state lifetimes, and steady-state and afterglow colours can all be systematically controlled by varying the cations and anions in the host inorganic phase, due to the influence of the cation size and material density on emissive and non-emissive electronic transitions. This simple strategy provides a flexible route for generating materials with specific, phosphorescent properties and is an exciting alternative to approaches relying on the synthesis of custom-made luminescent organic molecules.

On the Emission Properties of Carbon Dots: Reviewing Data and Discussing Models

“…Schneider et al [36] reported that faster decays are assigned to undoped nanoparticles, whilst a variable decay of about 8-10 ns, depending on the excitation, is the fingerprint of fluorescent molecules. Recently, a long-lasting phosphorescence emission was reported, with a lifetime of about a few seconds and a very small QY [59,60].…”

Preparation, functionalization and characterization of engineered carbon nanodots

“…CDs are considered quasi-spherical nanoparticles, with size below 10 nm, comprising carbon, oxygen and hydrogen atoms. Next to their apparently harmless, abundant and inexpensive nature, they have shown intriguing photoluminescence (PL) properties, which has brought them the label of "carbon nanolights" 7 and has sparked numerous applications [12][13][14][15][16][17][18][19][20] . CDs can be prepared via two main routes: top-down and bottom-up approaches 21,22 .…”

Ptychographic X-ray tomography reveals additive zoning in nanocomposite single crystals

“…The occlusion of additives ranging from small molecules, 7,32,53,54 to polymers, 34,55,56 to organic and inorganic nanoparticles, 4,5,8,18,22,24,26,28 in single crystals provides a unique strategy for creating new materials with tailor-made properties. However, to fully prot from this approach, it is necessary to control the composition and structure of these nanocomposites.…”

“…Nanocomposites are an exciting class of materials, where the ability to engineer compositions and structures at the nano-and meso-scales promises the ability to tailor electrical, optical, mechanical and catalytic properties, and to create multifunctionality. [1][2][3][4][5][6][7][8][9][10][11] One strategy for creating these materials is by dispersing nanoparticles within a continuous host matrix. While this approach has been widely explored for polymers, 1,[12][13][14] occlusion within inorganic matrices offers additional challenges, 11,15,16 where it is frequently difficult to control the microstructure and nanoparticles frequently accumulate at the grain boundaries in polycrystalline host matrices.…”