Spray-Deposited Aluminum-Doped Zinc Oxide as an Efficient Electron Transport Layer for Inverted Organic Solar Cells

Abstract
Spray-deposited thin films of zinc oxide (ZnO) and aluminum-doped zinc oxide (Al-ZnO) are characterized in detail to get insight into the role of a dopant in the matrix. ZnO and Al-ZnO are implemented as electron transport layers (ETLs) in inverted organic solar cells (IOSCs) with PTB7-Th as a donor and IEICO-4F as a nonfullerene acceptor, forming the bulk heterojunction (BHJ) photoactive layer. Organic solar cells (OSCs) based on the ZnO ETL exhibit a short-circuit current density (JSC) of 24.46 mA/cm2 and an open-circuit voltage (VOC) of 0.68 V, yielding a power conversion efficiency (PCE) of 9.3%. A solar cell based on the Al-ZnO ETL yields a higher JSC of 25.16 mA/cm2 and a VOC of 0.71 V, resulting in a PCE of 10.5%, which indicates that Al doping improves the device performance. Time-delayed collection field (TDCF) measurements yielded field-independent charge generation for both devices. Furthermore, steady-state photoluminescence (PL), time-resolved PL, and transient absorption measurements confirm reduction in the number of defect states in Al-ZnO thin films compared to ZnO thin films and efficient charge transfer, yielding an overall improved IOSC device performance.

Citation
Swami, S. K., Khan, J. I., Dutta, V., Lee, J., Laquai, F., & Chaturvedi, N. (2023). Spray-Deposited Aluminum-Doped Zinc Oxide as an Efficient Electron Transport Layer for Inverted Organic Solar Cells. ACS Applied Energy Materials. https://doi.org/10.1021/acsaem.2c03858

Acknowledgements
This publication is based upon work supported by the King Abdullah University of Science and Technology (KAUST) Office of Research Administration (ORA) under Award No: OSR-CARF/CCF-3079. The work is also supported by Basic Science Research Program through the National Research Foundation (NRF) of Korea funded by the Ministry of Education with Research Grant No. NRF-2022R1I1A1A01073859.

Publisher
American Chemical Society (ACS)

Journal
ACS Applied Energy Materials

DOI
10.1021/acsaem.2c03858

Additional Links
https://pubs.acs.org/doi/10.1021/acsaem.2c03858

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