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Matrix Technology Develops a-Si Technology for OLED Backplanes
Mattrix Technologies, a spin out of the University of Florida and a client of mine (IC08 Mattrix is the New NVerPix - with New Switches) has produced a bottom-emission, white-OLED display with an a-Si backplane. The pixels are based on Mattrix’s VOLET technology, a vertically arranged three-terminal device that combines the drive-TFT, storage capacitor, and OLED. They claim the following benefits:
The Net Present Values (NPVs - the value today of a longer term investment - editor) of greenfield OLED fab projects of all types are also substantially improved. This is a win-win for old fabs and new fabs. Any fab. The technology is a great fit for emissive TV technologies, and for LTPO replacement for mobile applications since you get the capabilities of a lower power display technology with options for refresh rate management.
The "secret sauce" is in multiple areas, from a proprietary nanocarbon source electrode (materials provided by JSR Corp.) to a slightly different driving method and the VOLET structure itself. A cross-sectional picture of the VOLET architecture is shown in the next figure. The demonstrator is shown in the next figure is a 4.7” WOLED panel made by Mattrix on a conventional a-Si backplane with no compensation provided by a Japanese contract manufacturer. It has brightness of 500 cd/m² and resolution of 85 dpi (TV demonstration). The increased aperture ratio of the panel yields a >250% increase in lifetime compared to control OLED devices.
Mattrix Technologies, a spin out of the University of Florida and a client of mine (IC08 Mattrix is the New NVerPix - with New Switches) has produced a bottom-emission, white-OLED display with an a-Si backplane. The pixels are based on Mattrix’s VOLET technology, a vertically arranged three-terminal device that combines the drive-TFT, storage capacitor, and OLED. They claim the following benefits:
- Reduced cost for the backplane needed
- Second, the current density in the vertical channel is 2-3x lower, expanding the design space such that lifetime can be improved,
- Displays can be made brighter. The vertical channel also decouples the current path from the gate-oxide interface, leading to less image burn-in.
- Emissive apertures are improved.
The Net Present Values (NPVs - the value today of a longer term investment - editor) of greenfield OLED fab projects of all types are also substantially improved. This is a win-win for old fabs and new fabs. Any fab. The technology is a great fit for emissive TV technologies, and for LTPO replacement for mobile applications since you get the capabilities of a lower power display technology with options for refresh rate management.
The "secret sauce" is in multiple areas, from a proprietary nanocarbon source electrode (materials provided by JSR Corp.) to a slightly different driving method and the VOLET structure itself. A cross-sectional picture of the VOLET architecture is shown in the next figure. The demonstrator is shown in the next figure is a 4.7” WOLED panel made by Mattrix on a conventional a-Si backplane with no compensation provided by a Japanese contract manufacturer. It has brightness of 500 cd/m² and resolution of 85 dpi (TV demonstration). The increased aperture ratio of the panel yields a >250% increase in lifetime compared to control OLED devices.
Matrix claims the backplane yield losses are 40% of the overall yield challenge in OLEDs. The author claims this technology makes LTPS less important. It makes IGZO less important. It allows companies with only basic a-Si capabilities and older fabs to compete in AMOLED. It radically changes the economics of new and old fabs in AMOLED: as a result, we might expect more AMOLED devices and faster conversion of price sensitive IT categories such as tablets and notebooks. The implications if it is adopted could be quite industry changing. Certainly, this is a very interesting development and while mass production may still be some years away, this is something we should all monitor as a new strategic option for the OLED industry.
Ian Hendy, ex Philips Exec and a fine display consultant, wrote the article provided but provided no specs on the reliably and mobility of the TFTs, a very strange way to discuss the subject. Since a-Si mobility is ~0.7 cm2.v*sec and LTPS is ~100 and IGZO ~20, a-Si TFTs needs to be 20 to 100 times larger, which would be a limiting factor on resolution. The larger TFTs, would reduce the aperture ratio, not increase it. It is unlikely that any panel maker would go the route of WRGB design for a smartphone due to the need for precise control, very high max luminance and absorbing 50% color filter losses. a-Si TFTs tend to suffer from wide variations in the gate voltage, which is a major problem for OLED’ drive TFTs, where the turn-on and turn-off voltages must be precisely controlled.
The claim that backplanes contribute 20% of the yield loss is absurd, as it tends to be in the 1% range out of the total yield loss of ~20%. The technique would be less expensive and use less masks than LTPS or IGZO but converting an LCD fab to OLEDs needs 3/4 of the OLED capex for the deposition and encapsulation process and more space for a comparable capacity. They there is the matter of LTPO and VRR, given that the cumulative number of OLED panels with LTPO for Samsung and Apple will be 350m+ going forward. And it’s likely that new OLED tablets and notebooks will use LTPO.
Ian Hendy, ex Philips Exec and a fine display consultant, wrote the article provided but provided no specs on the reliably and mobility of the TFTs, a very strange way to discuss the subject. Since a-Si mobility is ~0.7 cm2.v*sec and LTPS is ~100 and IGZO ~20, a-Si TFTs needs to be 20 to 100 times larger, which would be a limiting factor on resolution. The larger TFTs, would reduce the aperture ratio, not increase it. It is unlikely that any panel maker would go the route of WRGB design for a smartphone due to the need for precise control, very high max luminance and absorbing 50% color filter losses. a-Si TFTs tend to suffer from wide variations in the gate voltage, which is a major problem for OLED’ drive TFTs, where the turn-on and turn-off voltages must be precisely controlled.
The claim that backplanes contribute 20% of the yield loss is absurd, as it tends to be in the 1% range out of the total yield loss of ~20%. The technique would be less expensive and use less masks than LTPS or IGZO but converting an LCD fab to OLEDs needs 3/4 of the OLED capex for the deposition and encapsulation process and more space for a comparable capacity. They there is the matter of LTPO and VRR, given that the cumulative number of OLED panels with LTPO for Samsung and Apple will be 350m+ going forward. And it’s likely that new OLED tablets and notebooks will use LTPO.