High‐Efficiency Nonfullerene Organic Solar Cells Enabled by Atomic Layer Deposited Zirconium‐Doped Zinc Oxide

Abstract

Organic solar cells (OSCs) are promising photovoltaic devices and zinc oxide (ZnO) is a commonly used electron transport layer (ETL) in OSCs. However, the conventional spin-coating ZnO layer is currently limiting its efficiency potential. Herein, it is shown for the first time that atomic layer deposition (ALD), which allows for controlled thin film growth with atomic-scale control, can effectively be used to optimize the ZnO for nonfullerene OSCs. First, density functional theory (DFT) calculations are discussed to show the impact of doping ZnO with zirconium (Zr) on its density of states and detail the synthesis of Zr doped ZnO films by ALD using a supercycle approach. A 2.4% Zr concentration is found to be optimal in terms of optoelectronic properties and sufficiently low defect density. The champion efficiency of 14.7% for a PM6:N3-based nonfullerene OSC with Zr-doped ZnO ETL are obtained, which is %1% absolute higher compared to a device with an undoped ZnO ETL. This improvement is attributed to a lower series resistance, a suppressed surface recombination, and an enhanced current extraction resulting from the Zr-doped ZnO. This work demonstrates the potential of atomic-scale engineering afforded by ALD towards achieving the ultimate efficiency of OSCs.

Significant Stability Improvement of Fullerene Organic Photovoltaics via ZnO Film Modification through the Intermittent Spray Pyrolysis Technique

“…The chemical structures of the PTB7-Th polymer donor and PC 70 BM fullerene acceptor with the energy level alignment of the devices are illustrated in Figure 1 . The semiconductor band edge energy positions and the metal work functions were provided from refs ( 15 ), ( 20 ), ( 28 ), and ( 29 ).…”

Recent Progress in Advanced Organic Photovoltaics: Emerging Techniques and Materials

“…The acceptor alloy Y6:BTP-M in combination with donor PM6 delivered an outstanding PCE of 17.03 %. Figure 7f, g shows the energy level diagram and chemical structures of PM6, Y6 and BTP-M. Another derivative of Y6, N3, was studied in a PM6:N3-based solar cell by Poduval et al [124] In comparison to ZnO ETL, the device with Zr-doped ZnO ETL showed an increased PCE reaching 14.7 % in the inverted device structure.…”

Hole/Electron Transporting Materials for Nonfullerene Organic Solar Cells

“…and Zhang et al. doped ZnO with zirconium (Zr), which improved the optoelectronic properties and sufficiently lowered the defect density, thus improving the device performances of the related NF‐OSCs [18f,g] . Yu et al.…”