Media Releases

U of T researchers revolutionize technology used in electronic screens

October 31, 2011

Create world’s most efficient flexible organic light-emitting diodes on plastic

TORONTO, ON – Engi­neer­ing researchers at the Uni­ver­si­ty of Toron­to have devel­oped the world’s most effi­cient organ­ic light-emit­ting diodes (OLEDs) on plas­tic. This result enables a flex­i­ble form fac­tor, not to men­tion a less cost­ly, alter­na­tive to tra­di­tion­al OLED man­u­fac­tur­ing, which cur­rent­ly relies on rigid glass.

The results are report­ed online in the lat­est issue of Nature Pho­ton­ics.

OLEDs pro­vide high-con­trast and low-ener­gy dis­plays that are rapid­ly becom­ing the dom­i­nant tech­nol­o­gy for advanced elec­tron­ic screens. They are already used in some cell phone and oth­er small­er-scale appli­ca­tions.

Cur­rent state-of-the-art OLEDs are pro­duced using heavy-met­al doped glass in order to achieve high effi­cien­cy and bright­ness, which makes them expen­sive to man­u­fac­ture, heavy, rigid and frag­ile.

“For years, the biggest excite­ment behind OLED tech­nolo­gies has been the poten­tial to effec­tive­ly pro­duce them on flex­i­ble plas­tic,” says Mate­ri­als Sci­ence & Engi­neer­ing Pro­fes­sor Zheng-Hong Lu, the Cana­da Research Chair (Tier I) in Organ­ic Opto­elec­tron­ics.

Using plas­tic can sub­stan­tial­ly reduce the cost of pro­duc­tion, while pro­vid­ing design­ers with a more durable and flex­i­ble mate­r­i­al to use in their prod­ucts.

The research, which was super­vised by Pro­fes­sor Lu and led by PhD Can­di­dates Zhib­in Wang and Michael G. Helander, demon­strat­ed the first high-effi­cien­cy OLED on plas­tic. The per­for­mance of their device is com­pa­ra­ble with the best glass-based OLEDs, while pro­vid­ing the ben­e­fits offered by using plas­tic.

“This dis­cov­ery, unlocks the full poten­tial of OLEDs, lead­ing the way to ener­gy-effi­cient, flex­i­ble and impact-resis­tant dis­plays,” says Pro­fes­sor Lu.

Wang and Helander were able to re-con­struct the high-refrac­tive index prop­er­ty pre­vi­ous­ly lim­it­ed to heavy met­al-doped glass by using a 50–100 nanome­tre thick lay­er of tantalum(V) oxide (Ta2O5), an advanced opti­cal thin-film coat­ing mate­r­i­al. This advanced coat­ing tech­nique, when applied on flex­i­ble plas­tic, allowed the team to build the high­est-effi­cien­cy OLED device ever report­ed with a glass-free design.

The results of Wang and Helander’s work titled “Unlock­ing the Full Poten­tial of Organ­ic Light-Emit­ting Diodes on Flex­i­ble Plas­tic” are pub­lished online in the jour­nal Nature Pho­ton­ics (Nature Pho­ton­ics DOI: 10.1038/nphoton.2011.259). The full paper is avail­able at


A video inter­view with Michael G. Helander dis­cussing this research is avail­able at

Please con­tact Luke Y. H. Ng for images asso­ci­at­ed with this research dis­cov­ery.

For more infor­ma­tion, please con­tact:

Liam Mitchell
Com­mu­ni­ca­tions & Media Rela­tions Strate­gist
Engi­neer­ing Strate­gic Com­mu­ni­ca­tions
Fac­ul­ty of Applied Sci­ence & Engi­neer­ing
Office: 416–978-4498

Luke Y. H. Ng
Exter­nal Rela­tions & Stu­dent Life Offi­cer
Depart­ment of Mate­ri­als Sci­ence & Engi­neer­ing
Fac­ul­ty of Applied Sci­ence & Engi­neer­ing, Uni­ver­si­ty of Toron­to
Office: 416–946-3211