Intermediate Band (IB) solar cell is a concept belonging to the third generation of photovoltaic converters potentially having an efficiency limit exceeding the one of single gap solar cells. Its performance is based on the existence of an intermediate band within the conventional gap of a host semiconductor which facilitates two step absorptions of photons with energy below the band gap. An extension of intermediary band solar cells is the multiband solar cell achieved by increasing the number of IBs in the host gap. When the number of IBs increases to infinite, the device becomes equivalent to an infinite serial tandem, which exhibits a conversion efficiency close to the thermodynamic limit. One proposes a simple but accurate model for a multiband solar cell having an arbitrary number of IBs that may be implemented via Quantum Dot (QD) technology. The novelty of this approach lies in the computation procedure of the energy band diagram using the transfer matrix method and the derivation of an effective absorption coefficient for the IB system. The presented model is suitable as a tool for investigating electro-optical properties of QD multiband cells. Results of numerical simulations performed for finding maximum conversion efficiency for given architectures are presented.

Date Published: 5 May 2008
PDF: 8 pages
Proc. SPIE 7002, Photonics for Solar Energy Systems II, 70020T (5 May 2008); doi: 10.1117/12.779434

Published in SPIE Proceedings Vol. 7002:
Photonics for Solar Energy Systems II
Andreas Gombert, Editor(s)