Unprecedentedly Large Photocurrents in Colloidal PbS Quantum-Dot Solar Cells Enabled by Atomic Layer Deposition of Zinc Oxide Electron Buffer Layer

Authors
Jo, H.Kim, J.K.Kim, J.Seong, T.-Y.Son, H.J.Jeong, J.-H.Yu, H.
Issue Date
2021-12-27
Publisher
American Chemical Society
Citation
ACS Applied Energy Materials, v.4, no.12, pp.13776 - 13784
Abstract
Due to the excitonic nature, colloidal PbS quantum-dot solar cells have suffered from lower photocurrent densities than expected from the absorber band gap. The heterojunction between solution-processed ZnO and PbS quantum-dots has been predominantly explored for photovoltaic applications. However, the deeper conduction band minimum of typical PbS quantum-dots than that of solution-processed ZnO imposes a high electron barrier, limiting the short-circuit current densities of the resulting solar cells mostly below 30 mA/cm2. Here, we report that atomic layer deposition (ALD) of ZnO buffer at a low temperature can favor the interfacial band alignment and boost the photocurrent density over 35 mA/cm2 at PbS quantum-dot band gap of 1.18 eV. From our band structure analysis, the electron barrier with ALD-ZnO can be 0.55 eV lower compared to that with sol-gel ZnO. Furthermore, photoactivation of shallow gap states formed by hydroxyl species in ALD-ZnO induces band bending and efficient electron tunneling from PbS to ZnO. Due to the improved band alignment, the device with ALD-ZnO exhibits a significantly enhanced lifetime compared to that with sol-gel ZnO upon constant illumination at 1-sun. ? 2021 American Chemical Society.
Keywords
PHOTOVOLTAICS; TEMPERATURE; PERFORMANCE; ZNO; atomic layer deposition; colloidal quantum dot; photoactivation; solar cell; zinc oxide
ISSN
2574-0962
URI
https://pubs.kist.re.kr/handle/201004/115929
DOI
10.1021/acsaem.1c02511
Appears in Collections:
KIST Article > 2021
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