Si-OLED

Si-OLED (silicon organic light-emitting diode) is Epson's proprietary microdisplay technology, in which an OLED emissive layer is built directly on a single-crystal silicon wafer carrying CMOS drive circuitry. It is the image source in Epson's Moverio line of see-through augmented reality (AR) smart glasses. Because each pixel emits its own light, a Si-OLED panel needs no backlight, which lets unlit pixels render as true transparent black in an optical see-through display.

Si-OLED is one commercial example of the broader display class known as OLED-on-silicon (OLEDoS), the same family used by many Micro-OLED panels for near-eye displays. Epson introduced Si-OLED as the replacement for the LCD panels used in earlier Moverio models, first shipping it in the Moverio BT-300 (announced 2016).

How it works

A Si-OLED panel is an active-matrix OLED display whose backplane is a single-crystal (monocrystalline) silicon wafer rather than the glass substrate with thin-film transistors used in larger OLED panels. The transistors and pixel drivers are fabricated in the silicon as a CMOS integrated circuit, and the organic light-emitting stack is deposited on top of that circuit. Epson states that choosing silicon rather than glass for the base wafer allows more precise, smaller pixels, which is what makes a high-resolution panel possible at a fraction of an inch across.

Silicon is used as the backplane because its charge-carrier mobility is far higher than that of the amorphous or polycrystalline silicon thin-film transistors on glass, so the per-pixel drive circuitry can be shrunk to the size needed for thousands of pixels per inch. This is the defining property of all OLEDoS microdisplays, of which Si-OLED is one branded instance.

Color is produced using a white OLED emitter with a red-green-blue color filter array, rather than separately patterned red, green and blue emitters. A single white-emitting organic stack is deposited across all subpixels, and an RGB filter over each subpixel selects the color. This is a common approach for OLEDoS panels because depositing one uniform emitter is simpler to manufacture at microdisplay pixel pitches than aligning three separate emitter materials with a fine metal mask.

Because the OLED is self-emissive, a pixel that should be dark is simply switched off and emits no light. In a transparent AR display this means dark image regions let the real world show through, and only the lit pixels appear superimposed. Epson cites this as the reason Si-OLED reaches much higher contrast than its earlier backlit LCD, where the backlight leaks light even in nominally black areas.

Optical path in Moverio

The Si-OLED panel itself is tiny and sits in a projection engine mounted in the temple of the glasses. In the Moverio design the image is coupled into a thin molded light guide and travels by total internal reflection to a semi-reflective extractor (a half-mirror) positioned in front of each eye, which reflects the virtual image toward the pupil while still letting light from the real scene pass through. This makes Moverio an optical see-through head-mounted display. The BT-300 uses a temple-mounted optical engine feeding a roughly 10 mm-thick light guide with a curved half-tone extractor.

Specifications by Moverio generation

Epson's Moverio line moved from poly-silicon TFT LCD panels to Si-OLED with the BT-300, then to a higher-resolution Si-OLED panel with the BT-40 series. The table compares the display panels across these generations. The BT-200 row is the LCD predecessor included for contrast.

Model	Panel type	Panel size	Resolution (per eye)	Contrast ratio	Diagonal field of view	Year
Moverio BT-200	Poly-silicon TFT LCD	0.42 in	960 x 540	not specified	23 deg	2014
Moverio BT-300	Si-OLED	0.43 in	1280 x 720	100,000:1	23 deg	2016 (announced)
Moverio BT-40 / BT-40S	Si-OLED	0.453 in	1920 x 1080	500,000:1	34 deg	2021

The BT-300 panel carries 921,600 pixels (1280 x 720) on a 0.43-inch panel with 24-bit color, and Epson described it as the world's lightest binocular see-through smart glasses at announcement, at about 69 grams for the headset and more than 20 percent lighter than the BT-200. The 2021 BT-40 series moved to a 0.453-inch 1920 x 1080 Si-OLED panel at 60 Hz with 24-bit color, raising the diagonal field of view to 34 degrees and the contrast ratio to 500,000:1. Epson's own technology materials summarize the contrast improvement as a move from 230:1 on the BT-200 LCD to the later Si-OLED panels.

In November 2020 Epson described a fourth generation of its smart-glasses optical engine built around a 0.453-inch 1920 x 1080 Si-OLED panel rated at 500,000:1 contrast, which it said offered about 1.5 times the pixel density, 5 times the contrast and 1.5 times the field of view of the prior generation. This is the panel that shipped in the BT-40 series.

Relevance to VR and AR

Si-OLED matters to AR because optical see-through glasses have an unusual display requirement: the panel must add bright imagery over the real world while letting the user see through to dark or black regions. A backlit LCD cannot fully switch off, so its black level leaks light and the projected frame can wash out against a bright background. A self-emissive OLED-on-silicon panel switches dark pixels off entirely, so black image areas become transparent and contrast stays high. Epson's product manager Eric Mizufuka described the move from LCD backlit projection to Si-OLED as enabling higher contrast, a wider color gamut and true display transparency, and a hands-on review reported that the BT-300's image stayed clear against bright backdrops where the BT-200 had washed out.

The technology also addresses pixel density. Near-eye AR optics magnify a small panel to fill part of the user's vision, so visible pixel structure (the screen door effect) is a problem at low pixel pitch. Building the backplane on silicon lets Si-OLED pack a 1280 x 720 image onto a 0.43-inch panel in the BT-300 and a 1920 x 1080 image onto a 0.453-inch panel in the BT-40 series, pixel pitches that are difficult to reach with glass TFT backplanes.

Si-OLED is the AR-focused, Epson-branded member of the OLED-on-silicon family. The same OLEDoS approach, often marketed as Micro-OLED, is widely used for near-eye displays across augmented reality and virtual reality hardware, including electronic viewfinders and high-resolution VR headsets. A 2025 review in the journal Next Nanotechnology surveys OLEDoS for extended reality and notes the shared advantages of high contrast ratio, deep blacks and fast response that suit near-eye use, alongside the engineering challenges of the technology. Within that landscape, Si-OLED has been associated specifically with transparent binocular AR glasses rather than with fully immersive VR.

A practical limitation of self-emissive OLED microdisplays for AR is peak brightness. OLED-on-silicon panels are dimmer than some alternatives, which is a constraint for see-through use in bright daylight, and competing approaches such as RGB OLEDoS aim to raise brightness; Samsung Display, for example, demonstrated a high-brightness RGB OLEDoS microdisplay in 2026 targeting AR glasses.

Current status

As of 2026 Si-OLED remains the display technology Epson uses for its Moverio smart glasses, including the BT-40 series and the later BT-45 series, which pairs Si-OLED with a Full HD see-through binocular display at a 34-degree field of view and 500,000:1 contrast. Epson continues to position Moverio for enterprise and assisted-viewing uses rather than as a general consumer VR product, and the 0.453-inch 1920 x 1080 Si-OLED panel introduced with the BT-40 series in 2021 is the basis of the company's current optical engine.