The Electrical Behaviors of Grain Boundaries in Polycrystalline Optoelectronic Materials

Abstract

Polycrystalline optoelectronic materials are widely used for photoelectric signal conversion and energy harvesting, and play an irreplaceable role in the semiconductor field. As an important factor in determining the optoelectronic properties of polycrystalline materials, grain boundaries (GBs) have been the focus of research. Particular emphases have been placed on the generation and height of GB barriers, how carriers move at GBs, whether GBs act as carrier transport channels or recombination sites, and how to change the device performance by altering the electrical behaviors of GBs. This review introduces the evolution of GB theory and experimental observation history, classifies GB electrical behaviors from the perspective of carrier dynamics, summarizes carrier transport state under the external conditions such as bias and illumination and the related band bending. Then the carrier scattering at GBs and the electrical differences between GBs and twin boundaries are discussed. Lastly, the review describes how the electrical behaviors of GBs can be influenced and modified by treatments such as passivation or by consciously adjusting the distribution of grain boundary elements. By studying the carrier dynamics and the relevant electrical behaviors of GBs in polycrystalline materials, researchers can develop optoelectronics with higher performance.This article is protected by copyright. All rights reserved

Tuning Surface Electronics State of P-Doped In2.77S4/In(OH)3 toward Efficient Photoelectrochemical Water Oxidation

“…The brighter region corresponds to more positive V surface , while the darker region means a more negative V surface . 37 To plainly contrast the V surface changes with the nanosheet structure, the value of V surface plots is shown in Figure 3b, which is represented by the yellow downward arrow [cross over In 2.77 S 4 /In(OH) 3 ] and a clear V surface of 445 mV is observed from the line profile. Meanwhile, based on firstprinciples with the GGA-PBE functional, our theoretical calculations (Figure 3c) result indicates that the average potential energy of In 2.77 S 4 /In(OH) 3 is 6.637 eV related to the vacuum position.…”

“…A well-distinguishable color contrast in the surface potential map of In 2.77 S 4 /In­(OH) 3 is observed (Figure a), and the inset is the topographic image. The brighter region corresponds to more positive V surface , while the darker region means a more negative V surface . To plainly contrast the V surface changes with the nanosheet structure, the value of V surface plots is shown in Figure b, which is represented by the yellow downward arrow [cross over In 2.77 S 4 /In­(OH) 3 ] and a clear V surface of 445 mV is observed from the line profile.…”

Study of rutile TiO2(110) single crystal by transient absorption spectroscopy in the presence of Ce4+ cations in aqueous environment. Implication on water splitting

“…This is best done using a single crystal because the surface orientation and bulk structure have a higher chance of being reproduced. This is in addition to the absence of grain boundaries which also affect e-h generation and recombination [33,34]. Rutile TiO 2 (110) single crystal is the most understood prototype oxide semiconductor and probably the most stable.…”

Electron Transfer between Metal Ions and Photoexcited Semiconductors

“…To conduct the experiment, we used the most studied and probably understood n-type oxide semiconductor single crystal, the rutile TiO 2 (110), as a prototype. − The use of a single crystal is important as it removes possible effects of grain boundary, degree of crystallinity, and multiple surface orientations, among other factors. All affect the performance of polycrystalline photocatalysts and are poised to affect the TAS signal.…”