CdS quantum dot-sensitized solar cells based on nano-branched TiO2 arrays

Chang Liu,Lin Wei,Yanxue Chen,Liangmo Mei,Yitan Li,Cuncun Wu,Jun Jiao

doi:10.1186/1556-276x-9-107

Abstract

Nano-branched rutile TiO2 nanorod arrays were grown on F:SnO2 conductive glass (FTO) by a facile, two-step wet chemical synthesis process at low temperature. The length of the nanobranches was tailored by controlling the growth time, after which CdS quantum dots were deposited on the nano-branched TiO2 arrays using the successive ionic layer adsorption and reaction method to make a photoanode for quantum dot-sensitized solar cells (QDSCs). The photovoltaic properties of the CdS-sensitized nano-branched TiO2 solar cells were studied systematically. A short-circuit current intensity of approximately 7 mA/cm2 and a light-to-electricity conversion efficiency of 0.95% were recorded for cells based on optimized nano-branched TiO2 arrays, indicating an increase of 138% compared to those based on unbranched TiO2 nanorod arrays. The improved performance is attributed to a markedly enlarged surface area provided by the nanobranches and better electron conductivity in the one-dimensional, well-aligned TiO2 nanorod trunks.

Highlights

Solar cells have attracted considerable attention because of their potential application in low-cost and flexible energy generation devices
As the immersion time increases, the branches become greater in number and longer in length. These branches coated on TiO2 nanorod would greatly improve the specific surface area and roughness, which is urgent for solar cell applications
The resultant nanostructures consisted of single-crystalline nanorod trunks and a large number of short TiO2 nanobranches, which is an effective structure for the deposition of CdS quantum dots

Summary

Introduction

Solar cells have attracted considerable attention because of their potential application in low-cost and flexible energy generation devices. Compared to polycrystal TiO2 nanostructures, such as nanotubes and nanoparticles, nanobranched TiO2 nanorod arrays, which are grown directly on transparent conductive oxide electrodes, increase the photocurrent efficiency by avoiding the particle-to-particle hopping that occurs in polycrystalline films. These nanostructures could simultaneously offer a large surface area for deposition of CdS quantum dots, excellent lighttrapping characteristics, lower charge carrier recombination rates, and a highly conductive pathway for charge carrier collection, resulting in a highly efficient photoanode for solar cell applications

Methods

Results

Conclusion