Low-Temperature-Processed 9% Colloidal Quantum Dot Photovoltaic Devices through Interfacial Management of p-n Heterojunction

Randi Azmi, Havid Aqoma, Wisnu Tantyo Hadmojo, Jin Mun Yun, Soyeon Yoon, Kyungkon Kim, Young Rag Do, Seung Hwan Oh, Sung Yeon Jang

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Low-temperature solution-processed high-efficiency colloidal quantum dot (CQD) photovoltaic devices are developed by improving the interfacial properties of p-n heterojunctions. A unique conjugated polyelectrolyte, WPF-6-oxy-F, is used as an interface modification layer for ZnO/PbS-CQD heterojunctions. With the insertion of this interlayer, the device performance is dramatically improved. The origins of this improvement are determined and it is found that the multifunctionality of the WPF-6-oxy-F interlayer offers the following essential benefits for the improved CQD/ZnO junctions: (i) the dipole induced by the ionic substituents enhances the quasi-Fermi level separation at the heterojunction through favorable energy band-bending, (ii) the ethylene oxide groups containing side chains can effectively passivate the interfacial defect sites of the heterojunction, and (iii) these effects occur without deterioration in the intrinsic depletion region or the series resistance of the device. All of the figures-of-merit of the devices are improved as a result of the enhanced built-in potential (electric field) and the reduced interfacial charge recombination at the heterojunction. The benefits due to the WPF-6-oxy-F interlayer are generally applicable to various types of PbS/ZnO heterojunctions. Finally, CQD photovoltaic devices with a power conversion efficiency of 9% are achievable, even by a solution process at room temperature in an air atmosphere. The work suggests a useful strategy to improve the interfacial properties of p-n heterojunctions by using polymeric interlayers.

Original languageEnglish
Article number1502146
JournalAdvanced Energy Materials
Issue number8
StatePublished - 20 Apr 2016

Bibliographical note

Publisher Copyright:
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


  • conjugated polyelectrolytes
  • low-temperature process
  • p-n heterojunction
  • quantum dots
  • solar cells


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