Nanoscale analysis of a hierarchical hybrid solar cell in 3D

Abstract

A quantitative method for the characterization of nanoscale 3D morphology is applied to the investigation of a hybrid solar cell based on a novel hierarchical nanostructured photoanode. A cross section of the solar cell device is prepared by focused ion beam milling in a micropillar geometry, which allows a detailed 3D reconstruction of the titania photoanode by electron tomography. It is found that the hierarchical titania nanostructure facilitates polymer infiltration, thus favoring intermixing of the two semiconducting phases, essential for charge separation. The 3D nanoparticle network is analyzed with tools from stochastic geometry to extract information related to the charge transport in the hierarchical solar cell. In particular, the experimental dataset allows direct visualization of the percolation pathways that contribute to the photocurrent. The nanoscale morphology of a hierarchically structured photoanode for a hybrid solar cell is investigated. By performing electron tomography on a micropillar extracted from a complete device, and by using analytical tools from stochastic geometry, the 3D hierarchical network is quantitatively analyzed to determine the nanoscale structure of the photoanode. © 2014 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.