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Molecular-Layer-Engineered Inorganic-Organic Hybrid Materials

Final Report Summary - LAYERENG-HYBMAT (Molecular-Layer-Engineered Inorganic-Organic Hybrid Materials)

The combined ALD (atomic layer deposition) and MLD (molecular layer deposition) technique is now strongly emerging as a viable technology for the fabrication of state-of-the-art hybrid inorganic-organic thin films of exciting new functionalities and true application potential; the LAYERENG-HYBMAT project has had a central role in this progress. Within the five-year project we developed well-controlled ALD/MLD processes for a wide palette of metal (alkali and alkaline earth metals and several d-block transition metals and lanthanides) and organic (aryls, arenes, pyridines, natural nucleobases, photoresponsive azo molecules, etc.) constituents.

As one of the highlights of the new enabling functionalities we discovered unique upconversion luminescence properties for our hybrid thin films, relevant for e.g. future biosensor and solar cell applications. Another intriguing discovery was that by ALD/MLD it is possible to grow in-situ crystalline thin films of MOF (metal organic framework) type structures; our original discovery was for Cu-terephthalate films of the well-known paddle-wheel MOF structure. Later on, we also demonstrated the capacity of the ALD/MLD technique to yield crystalline metal-organic structures not even known before. A thrilling example was the lithium-quinone structure which turned out be a superior cathode material for a flexible organic microbattery. Another approach to novel crystalline hybrid materials was to build ordered superlattices and gradient laminates with thicker crystalline inorganic (ZnO, TiO2, ɛ-Fe2O3, etc.) layers and monomolecular organic layers. Such precisely layer-engineered thin films were shown to be useful for example for bandgap tuning and phonon blocking in applications ranging from optoelectronics to thermoelectrics.

Through the persistent research work carried out within the LAYERENG-HYBMAT project and the multiple material discoveries made, we were able to demonstrate the huge potential of the ALD/MLD technique as a scientifically elegant, yet industrially feasible way to fabricate new advanced materials, not necessarily accessible using conventional synthesis techniques. The ALD/MLD technique moreover enabled the deposition of these exciting new materials directly on sensitive/flexible/complex surfaces such as textiles for e.g. wearable applications.