Hierarchically self-assembled nanomaterials for high efficiency excitonic solar cells

The project proposes the preparation of innovative nanostructured photo-electrodes and their integration in high efficiency excitonic solar cells via spray pyrolysis technique. Quantum dot solar cells are based on photoexcitation of quantum dots (QDs) adsorbed onto the surface of metal oxide nanoparticles (TiO2, SnO2, ZnO). The QD harvests the incident light and injects electrons into the TiO2, where they percolate through the oxide nanoparticles to reach an electrode connected to the load. The QD is regenerated by hole injection into either a hole conductor or an electrolyte. In QDSCs the two main factors limiting photoconversion efficiency are the poor matching of the absorption characteristics of organic semiconductors and the solar spectrum, and the presence of charge recombination phenomena, which significantly limit charge collection in the operating device.
Much of the current research focuses on:
i) improving the range of spectral absorbance by modifying the QD;
ii) improving the optical density of the active layer to maximize the absorbed light;
iii) improving hole transport and cell stability by replacing the liquid electrolyte with ionic solids or conducting polymers;
iv) improving electron transport by using alternative wide-band-gap semiconductor materials.
The self-assembly of functional nano-materials, when combined with low-cost and versatile production techniques, opens perspectives critical to optimal use of natural resources and exploitation of high performance systems obtained by simplified approaches.
In this project we apply spray deposition for the production of new engineered nanomaterials, delivering hierarchical systems that meet the crucial requirements for a high efficiency excitonic solar cell, namely:
(1) high optical density of the optically active layer (light harvesters will be semiconducting QDs), allowing maximum light absorption in the spectral range of the sensitizer;
(2) high light scattering of the absorbing layer, enhancing the time spent by light inside the sensitized film and improving light absorption; and
(3) inhibition

Faculty Supervisor:

Federico Rosei


Jaskaran Singh Malhotra



Engineering - mechanical





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