Highly efficient organic light-emitting diodes with a silole-based compound

Abstract

Efficient light emission was obtained in a silole-based organic light-emitting diode. A high luminous current efficiency of 20 cd/A, corresponding to an external quantum efficiency of 8%, was achieved. The apparent violation of the upper theoretical limit of 5.5% for the external quantum efficiency of a singlet emitter is discussed. With a suitably designed cathode, a high power efficiency of ∼14 lm/W was obtained. A strong dependence of the power efficiency on the thickness of Alq3 layer is also observed and explained.

Optimizing the Charge Balance of Fluorescent Organic Light‐Emitting Devices to Achieve High External Quantum Efficiency Beyond the Conventional Upper Limit

“…However, recent studies have reported much higher EQEs than 5% of the classic upper limit. [5][6][7][8][9][10] For example, the Kodak group reported an 11% EQE in a red fl uorescent OLED, [ 10 ] and the SANYO group reported a 10% EQE in a green fl uorescent OLED. [ 6 ] A good charge balance is a very important prerequisite when discussing the effect of the other parameters that affect the EQE, such as the singlet-triplet exciton ratio and the outcoupling effi ciency.…”

Strong Luminescent Iridium Complexes with CˆN=N Structure in Ligands and Their Potential in Efficient and Thermally Stable Phosphorescent OLEDs

“…It has been widely accepted that for excitons generated by carrier injection, which is exactly the case in OLEDs, the ratio of singlet and triplet exciton is 1:3. Due to this intrinsic factor, although abnormal cases exist, [6,7] the internal quantum efficiency (IQE) of OLEDs employing fluorescent emitters is generally limited to 25%, while IQE of OLEDs utilizing phosphorescent emitters (PHOLEDs) can reach almost 100%. [3] Hence, due to this higher efficiency and motivated by the potential applications in flat panel displays (FPDs), solid-state lighting (SSL), and backlights for liquid-crystal displays (LCDs) based on OLED technology, PHOLED materials and devices have been intensively studied since the seminal work in 1998.…”

Blue Electrofluorescence Properties of Furan–Silole Ladder Pi-Conjugated Systems

“…Following the successful incorporation of thiophene oligomers and polymers in opto-electronic devices, [1][2][3] new derivatives featuring B [4,5], N [6,7], O [8,9], Si [10] or P [11][12][13][14][15][16][17][18][19] have been developed. In particular, siloles (silacyclopentadienes) found promising applications in the field of organic light emitting devices (OLEDs) [20][21][22][23]. Two main reasons explain the good behaviour of siloles in these devices.…”