Simon Ogier | SmartKem: Can low-mobility organic transistors actually drive ultra-bright microLED displays?
14:42 - 16:18
Other snippets from this talk
Summary of the clip:
Can low-mobility organic transistors actually drive ultra-bright microLED displays?
Skeptics often dismiss Organic Thin Film Transistors (OTFTs) for active-matrix displays due to their relatively low carrier mobility compared to LTPS or metal oxides. However, display brightness depends on a systemic balance between emitter efficiency, aperture ratio, and the drive current supplied by the transistor layout.
SmartKem's modeled and fabricated pixel layouts demonstrate that by optimizing the drive transistor's channel width-to-length ratio, OTFTs can supply ample current to achieve extreme luminance levels. In a 254 PPI display configuration, a dual-gate OTFT design successfully drives microLEDs to an impressive 40,000 nits.
Because the backplane is processed directly on top of downward-emitting microLEDs, the entire pixel area can be utilized for the drive circuitry without compromising the aperture ratio. This design freedom allows for wider transistor channels that easily overcome mobility limitations, offering a viable path for high-brightness signage and outdoor displays.
In this short video, you can learn:
* The physics of how optimized transistor dimensions compensate for lower organic semiconductor carrier mobility.
* Quantitative brightness benchmarks showing OTFTs driving microLEDs up to 40,000 nits.
* The architectural advantage of downward-emitting microLEDs in maximizing backplane circuit area.
π **Clip Abstract** This clip addresses the industry skepticism surrounding OTFT mobility limits when driving power-hungry microLED emitters. Simon Ogier provides quantitative data showing that optimized dual-gate organic backplanes can achieve brightness levels up to 40,000 nits.
π Link in comments π
#OTFT, #MicroLEDDisplays, #DualGateOTFT, #DownwardEmittingMicroLED, #ActiveMatrixBackplanes, #FlexibleElectronics
This is a highlight of the presentation:
More Highlights from the same talk.
08:33 - 10:39
Why are we still trying to transfer millions of microLEDs when we can print the backplane directly on top of them?
Why are we still trying to transfer millions of microLEDs when we can print the backplane directly on top of them?
Traditional microLED display manufacturing suffers from massive yield losses due to the delicate transfer and eutectic bonding processes required to connect individual chips to a pre-fabricated backplane. SmartKem reverses this entire manufacturing paradigm by fabricating Organic Thin Film Transistors (OTFTs) directly on top of the native microLED wafer.
By utilizing low-temperature liquid-coatable inks processed under 80Β°C, the organic semiconductor and dielectric layers can be deposited without damaging the underlying GaN microLED structures. Lithographically defined vias and sputtered metal contact layers replace the unreliable, high-thickness metal bumps and liftoff processes common to standard transfer schemes.
This monolithic approach has successfully demonstrated active-matrix displays on native sapphire wafers across multiple pitches down to 100 microns. The resulting stack provides a planarized, robust configuration where the drive circuitry sits natively on the emitter, bypassing the mechanical alignment and bonding bottlenecks of mass transfer.
In this short video, you can learn:
* How direct-on-wafer TFT fabrication eliminates the need for expensive eutectic bonding and liftoff steps.
* The role of low-temperature liquid-coatable dielectric and semiconductor inks in preserving GaN performance.
* Visual proof-of-concept displays operating at 100-micron and 1-millimeter pitches on native sapphire.
π **Clip Abstract** This clip explains how fabricating OTFT backplanes directly on native microLED wafers bypasses mass transfer alignment issues. Simon Ogier outlines the low-temperature photolithographic process used to establish reliable sputtered contacts without metal bumping.
π Link in comments π
#OTFT, #MonolithicIntegration, #DirectOnWafer, #OrganicSemiconductors, #MicroLEDDisplays, #PrintedElectronics
00:00:24 - 00:00:30
How does an ideal inverter maintain signal integrity in digital circuits?
How does an ideal inverter maintain signal integrity in digital circuits?
The speaker explains the fundamental operation of an inverter, the simplest logic gate, which is crucial for building more complex digital circuits. An inverter's primary function is to take a low signal and convert it to a high signal, or vice versa. Ideally, an inverter should ensure that any input voltage below the halfway point results in a high output, while any input voltage above the halfway point results in a low output.
The presentation details the behavior of an ideal inverter using an IV curve. When the input voltage (Vin) is low (zero), the output voltage (Vout) is high, close to the voltage rail. Conversely, when Vin is high, Vout is low. The ideal scenario is a sharp transition at the halfway point of the voltage range, ensuring a clear distinction between high and low signals.
Over time, as Vin changes, Vout should ideally follow in complete inverse. This ensures that the logic is flipped correctly and that the signal integrity is maintained throughout the circuit. Preserving this logic flipping is essential when multiple inverters are connected in series to build more complex circuits like processors.
In this short video, you can learn:
* The basic function of an inverter in digital logic.
* The ideal input-output voltage relationship of an inverter.
* The importance of maintaining signal integrity in cascaded logic gates.
π **Clip Abstract** This segment elucidates the core functionality of an inverter, emphasizing its role in signal inversion and the characteristics of an ideal inverter for maintaining logic integrity. It highlights the importance of a clear transition between high and low signals for reliable digital circuit operation.
π Link in comments π
#IdealInverter, #SignalIntegrity, #LogicGates, #VoltageTransferCharacteristic, #SemiconductorDevices, #DigitalElectronics
11:02 - 13:08
Can a "chip-first" transfer sheet approach slash microLED GaN material costs by over 95%?
Can a "chip-first" transfer sheet approach slash microLED GaN material costs by over 95%?
While monolithic fabrication on native sapphire works for small, ultra-fine-pitch displays, it becomes economically unviable for larger form factors because of the high cost of sapphire and GaN area. To solve this, a hybrid "chip-first" approach places microLEDs onto a temporary transfer sheet, effectively spreading them out to match the final display's pitch.
Once the microLEDs are spaced across the large-area transfer sheet, a thick dielectric layer planarizes the surface, covering the large step heights of the chips. Vias are then lithographically patterned down to the anode and cathode, allowing a single-piece backplane to be sputtered and processed directly on top of the assembly.
This strategy dramatically reduces the bill of materials, dropping the GaN cost of a smartwatch display from roughly $83 to just $2. Furthermore, by releasing the carrier glass, manufacturers can yield highly flexible, large-area microLED displays using standard photolithography and sputtering instead of fragile, expensive tiling methods.
In this short video, you can learn:
* The economic contrast between monolithic sapphire integration and the hybrid transfer sheet method.
* How thick dielectric planarization allows processing high-yield backplanes on top of transferred microLEDs.
* The pathway to scaling microLED displays up to Gen 8.5 fabrication lines without thermal evaporation or liftoff.
π **Clip Abstract** This clip introduces a hybrid "chip-first" manufacturing process that spreads microLEDs onto a transfer sheet before fabricating the OTFT backplane on top. This technique yields a dramatic reduction in GaN substrate costs while enabling thin, flexible display form factors.
π Link in comments π
#ChipFirstTransfer, #DielectricPlanarization, #OTFTBackplane, #MicroLEDTransfer, #FlexibleDisplays, #MicroLEDDisplays