High Brightness, Highly Directional Organic Light‐Emitting Diodes as Light Sources for Future Light‐Amplifying Prosthetics in the Optogenetic Management of Vision Loss

Abstract

Optogenetic control of retinal cells transduced with light‐sensitive channelrhodopsins can enable restoration of visual perception in patients with vision loss. However, a light intensity orders of magnitude higher than ambient light conditions is required to achieve robust cell activation. Relatively bulky wearable light amplifiers are currently used to deliver sufficient photon flux (>1016 photons/cm2/s in a ±10° emission cone) at a suitable wavelength (e.g., 600 nm for channelrhodopsin ChrimsonR). Here, ultrahigh brightness organic light‐emitting diodes (OLEDs) with highly directional emission are developed, with the ultimate aim of providing high‐resolution optogenetic control of thousands of retinal cells in parallel from a compact device. The orange‐emitting phosphorescent OLEDs use doped charge transport layers, generate narrowband emission peaking at 600 nm, and achieve a luminance of 684 000 cd m–2 at 15 V forward bias. In addition, tandem‐stack OLEDs with a luminance of 1 152 000 cd m–2 and doubled quantum efficiency are demonstrated, which greatly reduces electrical and thermal stress in these devices. At the photon flux required to trigger robust neuron firing in genetically modified retinal cells and when using heat sinking and realistic duty cycles (20% at 12.5 Hz), the tandem‐stack OLEDs therefore show a greatly improved half‐brightness lifetime of 800 h.

High-Brightness Blue Polariton Organic Light-Emitting Diodes

“…To make the device compatible with opaque substrates, as is required for example to maximize thermal conductivity in efforts toward electrically pumped lasers, the architecture of the device was not only adjusted for a bottom-emitting design (BE-POLED) but also for a top-emitting cavity design (TE-POLED). 24 BE-POLED and TE-POLED were fabricated by making either the anode or the cathode semitransparent. A third (reference) device was fabricated using indium tin oxide (ITO) as transparent electrode to compare its characteristics to the cavity devices.…”

“…We report two device configurations exhibiting strong light–matter interaction, namely, a bottom- and a top-emitting architecture. The top-emitting architecture is of significant interest for future (flexible) displays and high-current applications, both of which benefit from the ability to use opaque substrates . Our devices achieve a record external quantum efficiency (2.2%) and brightness (>20,000 cd/m 2 ) among the polariton OLEDs without an assistant strong coupling layer reported to date.…”

Wireless magnetoelectrically powered organic light-emitting diodes

“…2A . This allowed single-color emission and ensured high efficiency as well as high stability and excellent yield, even in the presence of a rough substrate ( 28 , 39 ). The transport layer thicknesses were optimized for maximum efficiency via optical transfer matrix modeling (fig.…”

“…OLEDs consist of stacks of several organic layers and typically have an overall thickness of less than 1 μm. They can emit light at any wavelength of the visible spectrum; for instance, to realize the red, green, and blue subpixels in a display or to address a particular photodynamic sensitizer ( 27 ) or optogenetic channel ( 28 ). Unlike inorganic LEDs, OLEDs are area emitters and can thus assume any two-dimensional shape, e.g., to match a geometrical constraint imposed by a particular application ( 29 ).…”

High‐Density Integration of Ultrabright OLEDs on a Miniaturized Needle‐Shaped CMOS Backplane

“…[ 25 ] Ensuring sufficient operational stability for these high brightness OLEDs is also challenging but can be achieved by careful choice of injection layers, suitable stack design and thin film encapsulation, the latter rendering the devices stable under a wide range of conditions, including even in water or inside biological tissue. [ 26–28 ]…”