Solar Technologies
The solar cell has evolved into new device geometries and new materials starting from monocrystal silicon to the present day semiconductor quantum dots (QDs) polymer composites. The device consists of three components: (a) Light absorbers such as short band-gap semiconductors which absorb solar light and generate charge carriers i.e. electrons and holes, (b) matrix that transport the carriers to (c) conducting electrode surface, which generates photocurrent.
Semiconductor quantum dots offer new opportunities to harvest light energy spanning the entire visible and IR regions of the electromagnetic spectrum. Materials such as silicon, CdSe, CdTe, PbSe, etc., have a range of tunable band gap QDs can be synthesized, and co-assembled in order to harvest the sunlight for conversion into electrical current. To enhance the photocharge transport, the quantum dots can be surface engineered appropriately.
As an example of constructing a QDs-polymer composite solar cell device , the following steps are adopted:
- synthesis of a range (size, shape and constituent materials) of colloidally prepared quantum dots, first with prototypical emitters such as ZnSe (UV), CdSe (Visible), PbSe (IR, that can be extended to various hybrid nanostructures, to provide a broad band solar spectrum response from the UV to IR and efficiently produce photogenerated charge carriers for subsequent transport;
- effective extraction and charge–separation of carriers at the quantum dot-polymer interface by the development of methods of quantum dot functionalization and attachment to single walled carbon nanotubes,
- optimization of the performance of photosensitizer nanostructures for obtaining high photovoltaic effect while enhancing the conductivity of the host polymer matrix, and (iv) testing the device performance in broad spectrum simulated solar light.
NanoAxis synthesizes various (visible to NIR emitting) cadmium based (AxiCad) QDs, such as CdTe/ZnTe and CdHgTe/ZnTe for application in solar cells.