Unprecedentedly Large Photocurrents in Colloidal PbS Quantum-Dot Solar Cells Enabled by Atomic Layer Deposition of Zinc Oxide Electron Buffer Layer
- Authors
- Jo, Hyemin; Kim, Jai Kyeong; Kim, Junghwan; Seong, Tae-Yeon; Son, Hae Jung; Jeong, Jeung-Hyun; Yu, Hyeonggeun
- Issue Date
- 27-12월-2021
- Publisher
- AMER CHEMICAL SOC
- Keywords
- colloidal quantum dot; solar cell; atomic layer deposition; zinc oxide; photoactivation
- Citation
- ACS APPLIED ENERGY MATERIALS, v.4, no.12, pp.13776 - 13784
- Indexed
- SCIE
SCOPUS
- Journal Title
- ACS APPLIED ENERGY MATERIALS
- Volume
- 4
- Number
- 12
- Start Page
- 13776
- End Page
- 13784
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/139015
- DOI
- 10.1021/acsaem.1c02511
- ISSN
- 2574-0962
- 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/cm(2). 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/cm(2) 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.
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