Intraband absorption in solar cells with an intermediate band

Abstract

This article presents a thermodynamic treatment of an intermediate band solar cell that includes photoinduced electronic transitions between two distinct states of the intermediate band. The treatment also allows for two black-body sources, interband photoinduced electronic transitions, overlapping absorption coefficients, multiple electron-hole pair generation, and nonradiative processes. A schematic of the device’s thermodynamic configuration shows that the solar cell is composed of three particle engines operating in tandem. The authors present detailed-balance results where it is assumed that when there is the physical possibility of both photoinduced intra- and interband electronic transitions at intermediate levels that the latter predominates. Results indicate that as the intermediate band’s width increases, the efficiencies saturate to those of two-stack tandem solar cells while the band structures approach that of a material that should operate as a black body. The authors conclude that the assumption that interband transitions predominate over intraband transitions, which is equivalent to ignoring or excluding intraband transitions, may yield results inconsistent with physical reality. The larger the difference between the intermediate band width and the smallest band gap in the system, the more pronounced will be the inconsistency.

Simudo: a device model for intermediate band materials

“…There have been a number of device models developed specifically for IB materials, mostly for solar cells, all in steady state. These include traditional [6,[28][29][30]and Boltzmann-approximation [31,32] detailed balance models, semianalytic models in the drift [33] and diffusion [24,34,35] limits, and PDD models [25][26][27]36]. The semianalytic models are specific to either the drift or diffusive limits, while the PDD models allow treatment of IB regions that are neither fully depleted nor fully quasi-neutral.…”

Temperature dependence of dark current properties of InGaAs/GaAs quantum dot solar cells

“…1 In order to make use of the low energy region ͑less than the band gap of GaAs͒ of solar spectrum, low dimensional structures have been introduced into III-V p-i-n structures, such as In͑Ga͒As quantum well 2,3 and quantum dots ͑QDs͒. [4][5][6][7] Many studies [8][9][10][11] indicate that incorporating QDs into the intrinsic region of a p-i-n solar cell can extend the photocurrent to longer wavelength, leading to a slightly increased short circuit current density. However, this is always accompanied by a reduction in the open circuit voltage ͑compared to the reference cells͒.…”

Initial theoretical study of solar cells with an intermediate band of non‐zero width and a thermalized electron population

“…In most of the investigated Δ E range, the optimal values of E ci and E iv decrease with Δ E . This deviates from the band gaps of the fundamental limit where they obtain a slight increase before they stabilize . The decrease in the optimal value of the sub‐band gaps is due to the low absorptivity for photons with energy slightly above the band gap.…”