| Autor: |
Farahat ME; Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada., Anderson MA; Department of Materials Science and Engineering, The University of Arizona, Tucson, Arizona 85721, United States., Martell M; Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada., Ratcliff EL; Department of Materials Science and Engineering, The University of Arizona, Tucson, Arizona 85721, United States.; Department of Chemistry and Biochemistry, The University of Arizona, 1306 E. University Way, Tucson, Arizona 85721, United States.; Department of Chemical and Environmental Engineering, The University of Arizona, 1133 E. James E Rogers Way, Tucson, Arizona 85721, United States., Welch GC; Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada. |
| Abstrakt: |
Roll-to-roll coating of conventional organic photovoltaic architectures in air necessitates low work function, electron-harvesting interlayers as the top interface, termed cathode interlayers. Traditional materials based on metal oxides are often not compatible with coating in air and/or green solvents, require thermal annealing, and are limited in feasibility due to interactions with underlying layers. Alternatively, perylene diimide materials offer easily tunable redox properties, are amenable to air coating in green solvents, and are considered champion organic-based cathode interlayers. However, underlying mechanisms of the extraction of photogenerated electrons are less well understood. Herein, we demonstrate the utilization of two N -annulated perylene diimide materials, namely, PDIN-H and CN-PDIN-H, in air-processed conventional organic photovoltaic devices, using the now standard PM6:Y6 photoactive layer. The processing ink formulation using cesium carbonate as a processing agent to solubilize the perylene diimides in suitable green solvents (1-propanol and ethyl acetate) for uniform film formation using spin or slot-die coating on top of the photoactive layer is critical. Cesium carbonate remains in the film, creating hybrid organic/metal salt cathode interlayers. Best organic photovoltaic devices have power conversion efficiencies of 13.2% with a spin-coated interlayer and 13.1% with a slot-die-coated interlayer, superior to control devices using the classic conjugated polyelectrolyte PFN-Br as an interlayer (ca. 12.8%). The cathode interlayers were found to be semi-insulating in nature, and the device performance improvements were attributed to beneficial interfacial effects and electron tunneling through sufficiently thin layers. The efficiencies beyond 13% achieved in air-processed organic photovoltaic devices utilizing slot-die-coated cathode interlayers are among the highest reported so far, opening new opportunities for the fabrication of large-area solar cell modules. |
