Intermediate band solar cell with non-ideal band structure under AM1.5 spectrum

Abstract

The limiting efficiency of an intermediate band solar cell with a non-ideal band structure is analyzed using the principle of detailed balance. Firstly, the impact of finite band width on the optimum band gap design for AM1.5 spectrum is examined. It is found that the band width may be a determining factor in the optimum band gap arrangement, but that the degradation in efficiency due to the band width up to -200 meV is moderate. It is also found that the band width can determine which band gap combination gives the highest global limiting efficiency. Further to the intermediate band width modification, the inclusion of band tails, analogous to those present in amorphous materials is discussed in terms of realizing an intermediate band using quantum dot arrays. In this model the worst case scenario is assumed, that of low absorption, but maximum emissivity at the band tail edge of the intermediate band. Results show that, with multiple band gap combinations giving several local peaks, the one giving the global maximum efficiency changes with band width. When band tails are included in a materials system proposed for implementing an intermediate band solar cell via quantum dot miniband formation significant drop off in efficiency is seen. The results taken together suggest the intermediate band width and any band tails should be considered in designs for intermediate band solar cells.

Theoretical Study of One-Intermediate Band Quantum Dot Solar Cell

“…Therefore, there are three upward energy transitions: VI , CI , and CV . VI represents valence to intermediate band, CI represents intermediate to conduction band, and CV represents the conventional and behaves like a blackbody flux density and according to the Roosbroeck-Shockley equation[19][20][21][22] is given by…”

Electrical equivalent model of intermediate band solar cell using PSpice

“…Many techniques have been proposed to increase the efficiency of solar cells. They are based on different processes and properties such as photon recycling, impact ionization, angle dependent selectivity, down-conversion and up-conversion (Schokley & Queisser 1961;Luque & Martı 1997;Bremner & Honsberg 2012;Luque et al 2013). In recent years, intermediate-band solar cells (IBSCS) have been proposed to exceed efficiency limitations of conventional single-junction cells (Nozik 2006).…”