10.1: Invited Paper: Roll‐to‐Roll Manufacturing of Functional Substrates and Encapsulation Films for Organic Electronics: Technologies and Challenges

Abstract

This paper reviews a roll-to-roll technology for manufacturing of functional films as substrates and encapsulation for flexible OLED display and lighting devices. These functional films comprise ultra-high permeation barrier performance and two different types of a transparent electrode. Flexible small molecule OLED devices have been manufactured in roll-to-roll and characterized discussing current challenges for flexible electronic device encapsulation.

Multicolor Luminescence Switching and Controllable Thermally Activated Delayed Fluorescence Turn on/Turn off in Carbazole–Quinoxaline–Carbazole Triads

“…4 In contrast, solution-processed devices have attracted great interest due to the manufacturing low-cost and possibility of large area deposition by either inkjet or roll-to-roll printing, but have still not proven their merits in terms of device efficiencies, where these simpler devices are clearly lagging behind vacuum sublimed OLEDs. 5,6 Unfortunately, in OLEDs the electrical current that drives the device generates emissive and nonemissive species in a ratio 1:3. This is due to the formation of triplet species, which are typically non-emissive at room temperature.…”

“…However, thermally evaporated OLEDs require large amounts of organic materials to be used and need special conditions to hold high vacuum in spacious evaporation chambers . In contrast, solution-processed devices have attracted great interest due to the manufacturing low cost and possibility of large area deposition by either inkjet or roll-to-roll printing but have still not proven their merits in terms of device efficiencies, where these simpler devices are clearly lagging behind vacuum-sublimed OLEDs. , …”

Organic Flexible Electronics

“…At present, inorganic/organic hybrid has been considered as one of the most effective barrier technologies of flexible OLEDs. Typical examples include ZnO/parylene C, SiN–acrylate–SiN, Al 2 O 3 /ZrO 2 /alucone, zinc‐tin‐oxide (ZTO)/ORMOCER/ZTO, polymer/graphite nanocomposites, etc. Specifically, a water vapor transmission rate (WVTR) of less than 10 −6 g m −2 d −1 and an oxygen transmission rate (OTR) as low as 10 −5 cm 3 m −2 d −1 should be achieved to develop sufficient barriers for OLEDs…”

“…The initial luminance (500 cd m −2 ) of this flexible OLEDs decreased by 6% after 2000 times of bending at the 7 mm radius. Roll‐to‐roll manufacturing of substrate and encapsulation of small‐molecule OLEDs are investigated by Fahlteich et al 10 cm × 10 cm flexible white OLEDs with three‐layered permeation barrier stacks have reached a WVTR down to 5 × 10 −5 g m −2 d −1 at ambient condition on both PET and PEN substrates. However, vacuum‐deposition‐based R2R processing for cost‐effective OLEDs with low energy consumption still remains a challenge.…”

Improving, characterizing and predicting the lifetime of organic photovoltaics

“…Although ultrathin flexible glass as a substrate and barrier is starting to gain attraction especially in the field of organic light emitting diodes (LEDs), the utilization for OPVs is currently limited [152].The best flexible candidates for environmental protection are the foil-based barrier films ranging from food barriers to multilayer ultra-barrier films with WVTR reaching up to 10 -6 g/m²/day. The barrier films are either commercially available from a variety of manufacturers (price is highly dependent on barrier performance) or manufactured in research laboratories using solution coating, vacuum deposition, sputtering, or atomic layer deposition (ALD) of metal oxides and polymer interlayers[153][154][155][156].…”