TiO2 Passivation Layer on ZnO Hollow Microspheres for Quantum Dots Sensitized Solar Cells with Improved Light Harvesting and Electron Collection.

Zhen Li,Hao Wang,Huiwen Yang,Huan Ma,Libo Yu

doi:10.3390/nano10040631

Zhen Li, Hao Wang + Show 3 more

Open Access

https://doi.org/10.3390/nano10040631

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Journal: Nanomaterials	Publication Date: Mar 28, 2020
Citations: 20	License type: CC BY 4.0

Affiliation: Hexi University

Abstract

Light harvesting and electron recombination are essential factors that influence photovoltaic performance of quantum dots sensitized solar cells (QDSSCs). ZnO hollow microspheres (HMS) as architectures in QDSSCs are beneficial in improving light scattering, facilitating the enhancement of light harvesting efficiency. However, this advantage is greatly weakened by defects located at the surface of ZnO HMS. Therefore, we prepared a composite hollow microsphere structure consisting of ZnO HMS coated by TiO2 layer that is obtained by immersing ZnO HMS architectures in TiCl4 aqueous solution. This TiO2-passivated ZnO HMS architecture is designed to yield good light harvesting, reduced charge recombination, and longer electron lifetime. As a result, the power conversion efficiency (PCE) of QDSSC reaches to 3.16% with an optimal thickness of TiO2 passivation layer, which is much higher when compared to 1.54% for QDSSC based on bare ZnO HMS.

Highlights

The collapse of current climate because of global warming and huge demand of energy have forced us to conduct extensive research on solar cells over the past decades
Design and decoration of an appropriate metal oxide semiconductor (MOS) architecture has been considered as an effective approach to improve light harvesting and electron transport in quantum dots sensitized solar cells (QDSSCs) [11], enhancing the photovoltaic performance
In view of these backgrounds, it can be found that ZnO surface modification with TiO2 has attracted interest of researchers to enhance photovoltaic performance of QDSSCs, because of the combination of excellent electron mobility of ZnO and high chemical stability of TiO2 [29]

Summary

Introduction

The collapse of current climate because of global warming and huge demand of energy have forced us to conduct extensive research on solar cells over the past decades. Our group’s previous research found that ~500 nm ZnO HMS can generate strong light scattering, improving the power conversion efficiency (PCE) of ZnxCd1−xSe QDSSC [25] Another factor that limits ZnO application as architecture in QDSSCs is that there are multiple surface defects in ZnO [26], which increase the charge recombination and result in the drop of short-circuit current (Jsc). Lou et al [30] reported a PCE of 1.97% for QDSSCs based on ZnO nanorods passivated with TiO2 as a barrier layer In view of these backgrounds, it can be found that ZnO surface modification with TiO2 has attracted interest of researchers to enhance photovoltaic performance of QDSSCs, because of the combination of excellent electron mobility of ZnO and high chemical stability of TiO2 [29]. The PCE of QDSSCs increased from 1.54% for bare ZnO HMS to 3.16% for TiO2-passivated ZnO HMS with an optimal thickness of passivation layer

Materials

Preparation Carbonaceous Spheres Templates

Fabrication of TiO2-Passivated ZnO Hollow Microspheres Photoanode

Characterization

Findings

Conclusions