Faradaic junction and isoenergetic charge transfer mechanism on semiconductor/semiconductor interfaces

Abstract

Energy band alignment theory has been widely used to understand interface charge transfer in semiconductor/semiconductor heterojunctions for solar conversion or storage, such as quantum-dot sensitized solar cells, perovskite solar cells and photo(electro)catalysis. However, abnormally high open-circuit voltage and charge separation efficiency in these applications cannot be explained by the classic theory. Here, we demonstrate a Faradaic junction theory with isoenergetic charge transfer at semiconductor/semiconductor interface. Such Faradaic junction involves coupled electron and ion transfer, which is substantively different from the classic band alignment theory only involving electron transfer. The Faradaic junction theory can be used to explain these abnormal results in previous studies. Moreover, the characteristic of zero energy loss of charge transfer in a Faradaic junction also can provide a possibility to design a solar conversion device with a large open-circuit voltage beyond the Shockley-Queisser limit by the band alignment theory.

Photovoltage memory effect in a portable Faradaic junction solar rechargeable device

“…We experimentally observe the quasi-Fermi levels of both electron and hole in a semiconductor at the same time. The results are in good agreement with our previous study 43 , in which a Faradaic junction indicates a characteristic of isoenergetic interfacial charge transfer and can minimize the interface energy loss. Therefore, the electron and hole quasi-Fermi levels in Si under illumination are exactly recorded by MnO x and CoO x , respectively.…”

Controlling the density of storable charge of surface faradaic layers on Fe2O3 photoanodes for solar rechargeable devices

“…Time-of-flight secondary-ion mass spectrometry (TOF-SIMS) was then used to investigate the interface ion transfer process by 18 O isotopic labeling in the electrolyte. 9,33 Fig. 2b and c indicates the 18 O depth profiles for Fe 2 O 3 and Ti–Fe 2 O 3 after I – t measurement at different potentials in the dark and under illumination, respectively.…”

Construction and excellent photoelectric synergistic anticorrosion performance of Z-scheme carbon nitride/tungsten oxide heterojunctions

“…Actually, conventional type-II heterojunctions hinder electron and hole recombination because of the limitation of charge transfer pathways, but sacrifice the intrinsic redox ability of the two single materials from a thermodynamic perspective. 15,16 The design of a Z-scheme heterojunction as an anticorrosion filler can not only solve the limitation of easy recombination of photogenerated electrons and holes, but also the redox ability will be enhanced because the electrons accumulate at higher energy levels while the holes accumulate at lower energy levels. Thus, the construction of Z-scheme heterojunctions based on WO 3 has great advantages from the perspective of photocathodic reduction of corrosion.…”