Open AccessRoll-to-roll fabrication of highly transparent Ca:Ag top-electrode towards flexible large-area OLED lighting application
Author(s) -
Dongxiang Wang,
Jacqueline Hauptmann,
Christian May,
Yvonne J. Hofstetter,
Yana Vaynzof,
Tobias Müller
Publication year - 2021
Publication title -
flexible and printed electronics
Language(s) - English
Resource type - Journals
ISSN - 2058-8585
DOI - 10.1088/2058-8585/abf159
Subject(s) - oled , fabrication , sheet resistance , transmittance , materials science , optoelectronics , electrode , evaporation , transparency (behavior) , flexible electronics , vacuum evaporation , thermal stability , electronics , nanotechnology , thin film , electrical engineering , layer (electronics) , computer science , chemistry , medicine , alternative medicine , physics , computer security , pathology , organic chemistry , engineering , thermodynamics
Transparency and bendability are some of the most attractive unique selling points for organic light-emitting diode (OLED) lighting, enabling a variety of new application possibilities for industrial and private end-users. The roll-to-roll (R2R) OLED fabrication based on thermal evaporation offers a fast, continuous-running solution for producing flexible OLEDs at a lower cost. In this work, R2R fabricated large-area highly transparent thermal co-evaporated Ca:Ag (2:1 vol.%) top-electrode with mean transmittance of 64% over the visible range and a corresponding sheet resistance of as low as 21 Ω sq −1 was achieved. By increasing the film thickness to 24 nm, the sheet resistance can be further reduced to 12 Ω sq −1 , albeit with a lower mean transmittance of 58%. The Ca:Ag electrode demonstrates a high mechanical durability through 1000 bending cycles, which is highly desirable as a characteristic for flexible electronics, as well as for the R2R fabrication. Finally, the stability of the Ca:Ag electrode in vacuum and ambient was studied as well.