Solar Cells Based on Organic-Inorganic Nanocomposites

SEM image of porous Si surface and cross-section after electrochemical etching.10a

We fabricated and tested a novel nanocomposite hybrid solar cell from porous Si infiltrated with small organic molecules4b,17a. The fabrication of the cell is a very simple and cost effective procedure. Organic/inorganic components are inexpensive materials and electrochemical etching is a very simple method which does not require any special facilities like high vacuum deposition, lithography or clean rooms. Moreover, this method can be applied to fabricate standalone porous Si thin membrane by reusing the same Si substrate and should considerably reduce the operational cost. In addition, such membrane based solar cells can be prepared as a flexible, lightweight thin film if the appropriate polymer filling is applied. This project was sponsored by NSF SBIR program and was supported by the Boeing Company and several photovoltaic local companies.

Another direction in the development of hybrid photovoltaics is the carbon nanotube- Si solar cells.  We demonstrated photovoltaic effect for nanohybrid structure based on single walled carbon nanotubes (SWNT) /n-type Si heterojunction 10a. The solar cell in this study was not optimized, therefore there is substantial potential for the following performance improvements which include: SWNT doping to increase nanotube conductivity, selection of an optimal film thicknesses to provide a balance between Si and SWNT absorption and the use of porous Si to reduce the reflection from Si surface 10a 11a. In addition, the simple and scalable SWNT wet deposition offers to create a variety of p-n junction with other n-type substrates other than crystalline Si, e.g. any crystalline thin film amorphous/nanoporous semiconductors (see more in the review 9a and book chapter 5a by I. A. Levitsky).

One of our latest developments is the solar cell comprised of carbon nanotubes only, where the heterojunction is statistically formed between nanotube bundles of different nature 3a. This is the first report in the world about all carbon nanotube diodes and solar cells.