Electronic paper in color by electrochromic materials and plasmonics
Doktorsavhandling, 2023

The most common display today is emissive. It produces its own light and emits it to the viewer's eye. A reflective display, also known as electronic paper, uses ambient light and reflects it to the viewer, just like a newspaper. Electronic paper has some advantages over emissive displays such as: lower power consumption and readability in sunlight. Today, electronic papers in color lack a desirable color gamut - the colors look bad. The purpose of this thesis is to investigate how structural colors, plasmonics and electrochromics can be used to increase the optical performance of electronic paper in color.
By using structural colors (metal-insulator-metal) and plasmonics, we could create highly reflective color pixels. The pixels could be made to turn ON and OFF using electrochromic materials. In this thesis, conjugated polymers (PProDOT-Me2 and PProDOP) or tungsten oxide were employed. The reflection difference between the ON and OFF states was 60%. This was better than previously reported values for other electrochromic materials.
If the electrochromic material instead was incorporated into the nanostructure (metal-electrochromics-metal), applying a voltage would then alter the color of the pixel. If tungsten oxide was used inside the structure, the color of one pixel could change, but it would not be able to span the whole visible spectra. If, instead, the conjugated polymer (PT34bT) was used inside the structure, the whole visible spectra could be accessed with one pixel.
To create a real display, it is not enough to have one pixel that can change color. Millions of pixels in a grid are necessary. This poses a problem since each pixel needs to be individually contacted. This can be overcome by using a matrix configuration such as a passive matrix (PM) or an active matrix (AM). This thesis investigates both these configurations. PM requires the color change to be strongly non-linear with the applied voltage. It must have memory such as hysteresis. This effect can be incorporated by utilizing an indium-tin-oxide electrode as a counter electrode to a metal working electrode coated with a conjugated polymer as electrochromic material. To avoid crosstalk between pixels, a photo patterned electrolyte was used.
Commercial thin-film transistor arrays were used for AM configuration. The red, green, and blue nanostructures were deposited on the array. The conjugated polymer PProDOT-Me2 is synthesized directly on individual pixels and switched without crosstalk.

electrochromism

reflective displays

plasmonic electronic paper

conjugated polymers

structural color

plasmonic

KE-salen, Kemigården 4
Opponent: Prof. Sabine Ludwigs, University of Stuttgart

Författare

Oliver Olsson

Chalmers, Kemi och kemiteknik, Tillämpad kemi

High-Contrast Switching of Plasmonic Structural Colors: Inorganic versus Organic Electrochromism

ACS Photonics,;Vol. 7(2020)p. 1762-1772

Artikel i vetenskaplig tidskrift

Comparison of Electrodeposited and Sputtered Tungsten Trioxide Films for Inorganic Electrochromic Nanostructures

ACS Applied Optical Materials,;Vol. 1(2023)p. 558-568

Artikel i vetenskaplig tidskrift

Oliver Olsson, Marika Gugole, Jolie C. Blake, Ioannis Petsagkourakis, Peter Andersson Ersman, Andreas Dahlin.* - Electrochromic Passive Matrix Display Utilizing Diode-Like Redox Reactions on Indium-Tin-Oxide

Oliver Olsson*, Marika Gugole, Jolie C. Blake, Maxim Chukharkin, and Andreas Dahlin. - Electronic paper by plasmonic electrochromic active matrix

Displays are an integrated part of our society. We use displays at work to email, and at home for leisure. The majority of current displays are emissive displays, which produce light and emit it to your eyes in order to create an image. Some of the disadvantages of this type of system include eye fatigue and high power consumption. A printed magazine or newspaper does not have these issues. Light is not emitted by a newspaper but reflected from external light sources such as the sun or incandescent home lighting. A display that reflects light instead of emitting it is called electronic paper. Currently, there is one commercialized technology (Amazon Kindle). However, color versions of this technology have less optical performance than desired. To overcome this we instead used structural colors and electrochromics. By fusing these two fields we have stepped closer to electronic paper in color. Inspired by peacock feathers we have created reflective color pixels. To turn the pixels ON and OFF novel materials such as electrically conductive plastic are used. These plastics can change color between transparent and black. This technology has shown promising results and with this thesis, further developments have been made.

Energisparande elektrokromiska platta hybridmaterial

Stiftelsen för Strategisk forskning (SSF) (EM16-0002), 2018-02-01 -- 2022-12-31.

Ämneskategorier

Fysik

Kemi

Annan elektroteknik och elektronik

Fundament

Grundläggande vetenskaper

ISBN

978-91-7905-859-3

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5325

Utgivare

Chalmers

KE-salen, Kemigården 4

Opponent: Prof. Sabine Ludwigs, University of Stuttgart

Mer information

Senast uppdaterat

2023-05-12