Ab initio simulation of charge transfer at the semiconductor quantum dot/TiO2 interface in quantum dot-sensitized solar cells

Xukai Xin, Bo Li, Jaehan Jung, Young Jun Yoon, Rana Biswas, Zhiqun Lin

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

Quantum dot-sensitized solar cells (QDSSCs) have emerged as a promising solar architecture for next-generation solar cells. The QDSSCs exhibit a remarkably fast electron transfer from the quantum dot (QD) donor to the TiO2 acceptor with size quantization properties of QDs that allows for the modulation of band energies to control photoresponse and photoconversion effi ciency of solar cells. To understand the mechanisms that underpin this rapid charge transfer, the electronic properties of CdSe and PbSe QDs with different sizes on the TiO2 substrate are simulated using a rigorous ab initio density functional method. This method capitalizes on localized orbital basis set, which is computationally less intensive. Quite intriguingly, a remarkable set of electron bridging states between QDs and TiO2 occurring via the strong bonding between the conduction bands of QDs and TiO2 is revealed. Such bridging states account for the fast adiabatic charge transfer from the QD donor to the TiO2 acceptor, and may be a general feature for strongly coupled donor/acceptor systems. All the QDs/TiO2 systems exhibit type II band alignments, with conduction band offsets that increase with the decrease in QD size. This facilitates the charge transfer from QDs donors to TiO2 acceptors and explains the dependence of the increased charge transfer rate with the decreased QD size.

Original languageEnglish
Pages (from-to)80-90
Number of pages11
JournalParticle and Particle Systems Characterization
Volume32
Issue number1
DOIs
StatePublished - 1 Jan 2015

Bibliographical note

Publisher Copyright:
© 2014 WILEY-VCH Verlag GmbH & Co. KGaA.

Keywords

  • Ab initio simulation
  • Bridging state
  • CdSe and Pbse quantum dots
  • Charge transfer
  • Quantum dot-sensitized solar cells

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