Water Evaporation Induced Conversion of CuSe Nanoflakes to Cu2−xSe Hierarchical Columnar Superstructures for High‐Performance Solar Cell Applications. (7th April 2015)

• Record Type: Journal Article
• Authors: Xu, Jun; Yang, Qingdan; Kang, Wenpei; Huang, Xing; Wu, Chunyan; Wang, Li; Luo, Linbao; Zhang, Wenjun; Lee, Chun‐Sing
• Is Part Of: Particle and particle systems characterization. Volume 32:Number 8(2015:Aug.)
• Page Start: 840
• Page End: 847
• Publication Date: 2015-04-07
• Subjects: Particles -- Periodicals; 620.43
• DOI: 10.1002/ppsc.201400253
• Languages: English
• ISSNs: 0934-0866

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <p>In this work, a facile and low‐temperature water evaporation approach to prepare columnar superstructures consisting of face centered cubic (fcc) Cu<sub>2−<italic>x</italic></sub>Se nanoflakes stacked along 〈111〉 direction is reported. Formation of such unique stacked nanoflake assemblies is resulted from oriented attachment of isolated hexagonal CuSe nanoflakes along the 〈001〉 direction with a ripening effect driven by solvent evaporation, and then followed by a phase conversion into fcc Cu<sub>2−<italic>x</italic></sub>Se. Evolution from hexagonal CuSe nanoflakes to fcc Cu<sub>2−<italic>x</italic></sub>Se columnar superstructures results in obvious red‐shift of band‐gap absorption edge from 670 to 786 nm and dramatically decreased Raman resonance band intensity of the Se–Se stretching mode at 259 cm<sup>−1</sup> due to the phase conversion and composition variation. Remarkably, the Cu<sub>2−<italic>x</italic></sub>Se columnar superstructures are employed as low‐cost and highly efficient counter electrodes (CEs) in quantum dot sensitized solar cells, exhibiting excellent electrocatalytic activity for polysulfide electrolyte regeneration. A ZnSe/CdSe cosensitized solar cell using the Cu<sub>2−</sub><italic><sub>x</sub></italic>Se CE shows a significant increase in fill factor and short‐current density (<italic>J</italic><sub>SC</sub>) and yields a 128% enhancement in power conversion efficiency as compared to the traditional noble metal Pt CE.</p> </abstract>