ORGANIC LIGHT-EMITTING DIODE WITH ENHANCED LIGHT-EMITTING EFFICIENCY AND COLOR PURITY

專利類型

發明

專利國別 (專利申請國家)

美國

專利申請案號

16/354,826

專利證號

US 10,784,458 B1

專利獲證名稱

ORGANIC LIGHT-EMITTING DIODE WITH ENHANCED LIGHT-EMITTING EFFICIENCY AND COLOR PURITY

專利所屬機關 (申請機關)

元智大學

獲證日期

2020/09/22

技術說明

在有機發光二極體的發展過程中，提高藍光有激發光二極體的壽命一直是發展重點之一。原因在於藍光的光子能量高，使藍光有機發光材料容易衰變。明確而言，藍光有機發光二極體中激子-極化子消滅(exciton-polaron annihilation)的機制活躍，其中激子因壽命長，易與極化子作用而形成高能量的極化子。這樣的高能量極化子容易打斷發光材料中的分子鏈結，降低藍光發光材料的壽命。 此外，由於單重態激子回到基態可發螢光，而螢光材料中的三重態激子無法回到單重態進行放光，但正極化子與負極化子結合後形成三重態激子的機率高達75%，因此形成能量上的浪費。 現有技術中提出一種有機發光二極體，使用敏化層與發光層之間進行三重態-三重態能量轉移，以使發光層內發生三重態-三重態消滅上轉換。藉此，本發明可利用三重態能量進行發光，且使正極化與負極化激子在敏化層結合，提高有機發光二極體的壽命並同時提高效率。 然而，上述方案所提供的有機發光二極體中，當敏化層的單重態能量回到基態而放出的色光與發光層所放色光不同，將影響發光層所放色光的色純度。 緣此，本發明提出一種有機發光二極體，在敏化層中摻雜發光材料，以使敏化層的單重態能量轉移至摻雜材料的三重態能階，藉此以提升發光層所放色光的色純度。 As the development of OLED progresses, to extend the lifespan of blue light OLED has been an important issue, the reason being the photons of blue light possess higher energy than that of other colors, and therefore decay faster than the latter. Specifically, exciton-polaron annihilation mechanism exists in blue light OLEDs, wherein excitons exhibit long lifespan and tend to form high-energy excitons together with polarons. High energy polarons tend to break molecular bonds in light-emitting materials, decreasing the lifespan of light-emitting materials that emit blue light. In addition, only excitons of singlet energy fall back to the ground state and emit fluorescent light, and that of triplet energy can’t fall back to the ground state. However, the probability that positive polarons and negative polarons recombine and form triplet-energy excitons is as high as 75 percent, resulting in the waste of energy. Consequently, a prior art solution is proposed an organic light-emitting diode with a sensitizer layer, which perform triplet-triplet energy transfer with the light-emitting layer such that triplet-triplet annihilation upconversion mechanism is triggered in the light-emitting layer. In this way, the OLED of the present invention utilizes triplet energy to emit light, and enables the positive and negative excitons to recombine in the sensitizer layer, thereby enhancing the efficiency of the OLED and extending the lifespan thereof. However, when the above-mentioned OLED includes a sensitizer that emits light of a color different from that of light emitted by the light-emitting layer, the color purity of the light-emitting layer may be decreased. Therefore, we propose an OLED including a doped sensitizer, in which the singlet energy of the sensitizer is transferred to the triplet energy level of the dopant, and further transferred to the triplet energy level of the sensitizer, thereby enhancing the color purity of the light-emitting layer.

備註

連絡單位 (專責單位/部門名稱)

產學合作組

連絡電話

(03)4638800#2286

網址