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Content archived on 2024-06-16

Nanocrystalline heterosupermolecular materials for optoelectronic applications

Final Report Summary - HETEROMOLMAT (Nanocrystalline heterosupermolecular materials for optoelectronic applications)

The HETEROMOLMAT project engaged in the use of nanocrystalline semiconductor materials for optoelectronic applications. Specifically, the project focused on the following:
- hybrid light emitting diodes: this device laid on interfacing light emitting polymers with nanocrystalline semiconductor nanoparticles. The advantage induced was the non-use of highly unstable metal cathodes such as calcium or barium. Gold or even aluminum, instead, could be used as metal contacts, thus enhancing the device's life time;
- light-coupled chemical sensors for toxic substances: based on the design and synthesis of molecules it was shown that the binding of a toxic substance, such as mercury ions, could induce change in their optical properties. The molecules could be attached to the surface of mesoporous metal oxide films for deep-and-read test using inexpensive equipment;
- near-infrared (NIR) light-to-energy conversion devices: the aim was to highlight the possibility of achieving long-lived charge-separated states on NIR dye sensitised nanocrystalline metal oxide nanoparticles. There was a growing interest on harvesting the sunlight at wavelengths greater than 700 nm and achieving light-to-electricity conversion efficiencies higher than 3.5 %

Regarding the first project activity, the project succeeded in increasing the efficiency of the hybrid light-emitting diode, namely 10 candela/m2. The research also achieved a turn-on voltage of 5 V, as well as a stable light-emitting device operating in air (non-encapsulated). Thorough studies into the sensitivity of colometric sensors and into miniaturising them have been performed. Moreover, alternative dyes were studied, which due to their supermolecular structure could be implemented in miniaturised electrochemical devices, as well as possible market applications of the mercury sensor were investigated. Finally, one of the most challenging issues was the synthesis of suitable NIR dyes able to efficiently convert sunlight into electrical power. The sensitisation of metal oxides with NIR dyes was usually associated with inefficient devices. Based on the synthesis of phthalocyanines and on proper device preparation several world record cells were achieved. The results obtained using NIR dyes for solar-to-energy conversion devices paved a new way to harvest efficiently the whole solar spectrum using organic molecules