Multi-junction device

Efforts are currently underway to fabricate and test prototype a-Si Ge/Fe203 hybrid devices. With the University of Toledo, we completed an evaluation of a-Si Ge device yield on different metal-foil substrates, and a series of multi-junction devices... 

Fabricated initial set of multi-junction a-Si Ge devices for use in preliminary hybrid photoelectrode tests (with the University of Toledo). 

As discussed in Sect. 7.3.1, fundamental thermodynamics limits conversion efficiency for both single- and multijunction semiconductor PEC devices have also been established in numerous studies. The thermodynamic tandem limit under ideal conditions, i.e., including thermalization loss, but with no overpotential loss, has been calculated at approximately 40% STH. This is consistent with the optical limits shown in Fig. 7.23. It is also substantially higher than the 30% STH limit established for the single-junction case. Moreover, employing advanced multi-exciton device schemes which eliminate part of the thermalization loss, the theoretical tandem limit is further increased to 46% STH [58]. 

Figure 4.86. Schematic of (a) a single-junction and (b) multi-junction photovoltaic ceU. The single-junction cell is reproduced with permission from Kasap, S. O. Principles of Electronic Materials and Devices, 3rd ed., McGraw-Hill New York, 2007. Copyright 2007 The McGraw-Hill Companies.

J. Gilot and R. A. J. Janssen, Tandem and multi-junction organic solar cells, in Organic Solar Cells Fundamentals, Devices, and Upscaling, ed. B. P. Rand and H. Richter, Pan Stanford Publishing Pte. Ltd, 2014. 

When one views the membrane as a multi-layer thin film device, he begins to understand how the interphases control its electrophysical properties and the reaction rates across its junctions (18) (29). 

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