Efficiency limit and example of a photonic solar cell

• Published in: Journal of applied physics Vol. 110; no. 4; pp. 043104 - 043104-5
• Main Authors: Peters, Marius, Christoph Goldschmidt, Jan, Bläsi, Benedikt
• Format: Journal Article
• Language: English
• Published: American Institute of Physics 15.08.2011
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.3622669

Restricting the angular emission characteristics of a solar cell results in a reduction of entropy generation and allows for higher solar cell efficiencies. In this paper, we present the concept of a photonic solar cell which exhibits the combination of a solar cell and a photonic crystal. The basic idea is to structure a solar cell in such a way that the applied structure is a photonic crystal consisting of the solar cell material. The aim of having a solar cell in the form of a photonic crystal is to restrict the emission of the solar cell into certain angles This reduction reduces the radiative losses and results in a higher V OC and, consequently, a higher efficiency of the cell. To calculate the efficiency of a photonic solar cell we introduce an adaptation of the detailed balance approach. This adaptation takes into account the reduced radiative losses due to the presence of a photonic band structure. In the second part of the paper we use this approach to calculate the efficiency for an exemplary system. The exemplary system is an idealized edge filter, similar to a Bragg stack. The idealization concerns the reflection characteristic of this filter and its dependence on the polarization. For this idealized system we calculate an efficiency that exceeds that of a conventional solar cell by up to 2.5% absolute.