Nanoscale 2012-02-21

Core-shell structured photovoltaic devices based on PbS quantum dots and silicon nanopillar arrays.

Tao Song, Fute Zhang, Xiaofei Lei, Yonglan Xu, Shuittong Lee, Baoquan Sun

Index: Nanoscale 4(4) , 1336-43, (2012)

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Abstract

We fabricated three-dimensional silicon nanopillar array (SiNP)-based photovoltaic (PV) devices using PbS quantum dots (QDs) as the hole-transporting layers. The core-shell structured device, which is based on high aspect ratio SiNPs standing on roughed silicon substrates, displays a higher PV performance with a power conversion efficiency (PCE) of 6.53% compared with that of the planar device (2.11%). The enhanced PCE is ascribed to the increased light absorption and the improved charge carrier collections in SiNP-modified silicon surfaces. We also show that, for the core-shell structured device, the thickness of the shell layer plays a critical role in enhancing the PV performance and around five monolayers of QDs are preferred for efficient hole-transporting. Wafer-scale PV devices with a radial PbS/SiNP heterojunction can be fabricated by solution phase techniques at low temperatures, suggesting a facile route to fabricate unique three-dimensional nanostructured devices.This journal is © The Royal Society of Chemistry 2012