In situ formation and photo patterning of emissive quantum dots in small organic molecules

Nanostructured composites of inorganic and organic materials are attracting extensive interest for electronic and optoelectronic device applications. Here we report a novel method for the fabrication and patterning of metal selenide nanoparticles in organic semiconductor films that is compatible with solution processable large area device manufacturing. Our approach is based upon the controlled in situ decomposition of a cadmium selenide precursor complex in a film of the electron transporting material 1,3,5-tris(N-phenyl-benzimidazol-2-yl)-benzene (TPBI) by thermal and optical methods. In particular, we show that the photoluminescence quantum yield (PLQY) of the thermally converted CdSe quantum dots (QDs) in the TPBI film is up to 15%. We also show that laser illumination can form the QDs from the precursor. This is an important result as it enables direct laser patterning (DLP) of the QDs. DLP was performed on these nanocomposites using a picosecond laser. Confocal microscopy shows the formation of emissive QDs after laser irradiation. The optical and structural properties of the QDs were also analysed by means of UV-Vis, PL spectroscopy and transmission electron microscopy (TEM). The results show that the QDs are well distributed across the film and their emission can be tuned over a wide range by varying the temperature or irradiated laser power on the blend films. Our findings provide a route to the low cost patterning of hybrid electroluminescent devices

Initial Steps of Rubicene Film Growth on Silicon Dioxide

The film growth of the conjugated organic molecule rubicene on silicon dioxide was studied in detail. Since no structural data of the condensed material were available, we first produced high quality single crystals from solution and determined the crystal structure. This high purity material was used to prepare ultrathin films under ultrahigh vacuum conditions, by physical vapor deposition. Thermal desorption spectroscopy (TDS) was applied to delineate the adsorption and desorption kinetics. It could be shown that the initial sticking coefficient is only 0.2 ± 0.05, but the sticking coefficient increases with increasing coverage. TDS further revealed that first a closed, weakly bound bilayer develops (wetting layer), which dewets after further deposition of rubicene, leading to an island-like layer. These islands are crystalline and exhibit the same structure as the solution grown crystals. The orientation of the crystallites is with the (001) plane parallel to the substrate. A dewetting of the closed bilayer was also observed when the film was exposed to air. Furthermore, Ostwald ripening of the island-like film takes place under ambient conditions, leading to films composed of few, large crystallites. From TDS, we determined the heat of evaporation from the multilayer islands to be 1.47 eV, whereas the desorption energy from the first layer is only 1.25 eV

In situ formation and photo patterning of emissive quantum dots in organic small molecules

Nanostructured composites of inorganic and organic materials are attracting extensive interest for electronic and optoelectronic device applications. Here we report a novel method for the fabrication and patterning of metal selenide nanoparticles in organic semiconductor films that is compatible with solution processable large area device manufacturing. Our approach is based upon the controlled in-situ decomposition of cadmium selenide precursor complex in a film of the electron transporting material 1,3,5-tris(N-phenyl-benzimidazol-2-yl)-benzene (TPBI) by thermal and optical methods. Specifically we show that the photoluminescence quantum yield (PLQY) of the thermally converted CdSe quantum dots (QDs) in the TPBI film is up to 15%. We also show that laser illumination can form the QDs from the precursor. This is an important result as it enables direct laser patterning (DLP) of the QDs. DLP was performed on these nanocomposites using a picosecond laser. Confocal microscopy shows the formation of emissive QDs after laser irradiation. The optical and structural properties of the QDs were also analysed by means of UV-Vis, PL spectroscopy and transmission electron microscopy (TEM). The results show that the QDs are well distributed across the film and their emission can be tuned over a wide range by varying the temperature or irradiated laser power on the blend films. Our findings provide a route to the low cost patterning of hybrid electroluminescent devices

In situ formation and photo patterning of emissive quantum dots in organic small molecules

We acknowledge financial support from FP7 LAMP project “Laser Induced Synthesis of Polymeric Nanocomposite Materials and Development of Micro-patterned Hybrid Light Emitting Diodes (LED) and Transistors (LET)” (Grant No. 247928). AKB and IDWS also acknowledge financial support from EPSRC Programme grant “Challenging the limits of photonics: Structured light” EP/J01771X/1. In addition IDWS acknowledges a Royal Society Wolfson Research Merit Award.Nanostructured composites of inorganic and organic materials are attracting extensive interest for electronic and optoelectronic device applications. Here we report a novel method for the fabrication and patterning of metal selenide nanoparticles in organic semiconductor films that is compatible with solution processable large area device manufacturing. Our approach is based upon the controlled in-situ decomposition of cadmium selenide precursor complex in a film of the electron transporting material 1,3,5-tris(N-phenyl-benzimidazol-2-yl)-benzene (TPBI) by thermal and optical methods. Specifically we show that the photoluminescence quantum yield (PLQY) of the thermally converted CdSe quantum dots (QDs) in the TPBI film is up to 15%. We also show that laser illumination can form the QDs from the precursor. This is an important result as it enables direct laser patterning (DLP) of the QDs. DLP was performed on these nanocomposites using a picosecond laser. Confocal microscopy shows the formation of emissive QDs after laser irradiation. The optical and structural properties of the QDs were also analysed by means of UV-Vis, PL spectroscopy and transmission electron microscopy (TEM). The results show that the QDs are well distributed across the film and their emission can be tuned over a wide range by varying the temperature or irradiated laser power on the blend films. Our findings provide a route to the low cost patterning of hybrid electroluminescent devices.Publisher PDFPeer reviewe