Han-Cheng Yeh

Continuous blade coating for multi-layer large-area organic light-emitting diode and solar cell

A continuous roll-to-roll compatible blade-coating method for multi-layers of general organic semiconductors is developed. Dissolution of the underlying film during coating is prevented by simultaneously applying heating from the bottom and gentle hot wind from the top. The solvent is immediately expelled and reflow inhibited. This method succeeds for polymers and small molecules. Uniformity is within 10% for 5 cm by 5 cm area with a mean value of tens of nanometers for both organic light-emitting diode (OLED) and solar cell structure with little material waste. For phosphorescent OLED 25 cd/A is achieved for green, 15 cd/A for orange, and 8 cd/A for blue. For fluorescent OLED 4.3 cd/A is achieved for blue, 9 cd/A for orange, and 6.9 cd/A for white. For OLED with 2 cm by 3 cm active area, the luminance variation is within 10%. Power conversion efficiency of 4.1% is achieved for polymer solar cell, similar to spin coating using the same materials. Very-low-cost and high-throughput fabrication of efficient ...

Polymer Infrared Proximity Sensor Array

A near-infrared proximity sensor array is achieved by integrating a polymer light-emitting diode and a polymer photodetector (PD). A green emission is converted into deep red peaked at 670 nm by the inorganic phosphor Intematix R670 with quantum efficiency of over 20%. A bandpass filter is used to select a spectral tail of phosphor luminescence with a wavelength above 700 nm. The emissive polymer is green polyfluorene. The infrared PD contains a thick film of a blend of poly(3-hexylthiophene) and (6,6)-phenyl-C61-butyric acid methyl ester up to a thickness of 8 m. Position of a moving object at a distance of 10 cm is detected in real time by the array with dynamic images displayed on the computer screen.

Blade-coated sol-gel indium-gallium-zinc-oxide for inverted polymer solar cell

The inverted organic solar cell was fabricated by using sol-gel indium-gallium-zinc-oxide (IGZO) as the electron-transport layer. The IGZO precursor solution was deposited by blade coating with simultaneous substrate heating at 120 °C from the bottom and hot wind from above. Uniform IGZO film of around 30 nm was formed after annealing at 400 °C. Using the blend of low band-gap polymer poly[(4,8-bis-(2-ethylhexyloxy)-benzo(1,2-b:4,5-b’)dithiophene)-2,6-diyl-alt- (4-(2-ethylhexanoyl)-thieno [3,4-b]thiophene-)-2-6-diyl)] (PBDTTT-C-T) and [6,6]-Phenyl C71 butyric acid methyl ester ([70]PCBM) as the active layer for the inverted organic solar cell, an efficiency of 6.2% was achieved with a blade speed of 180 mm/s for the IGZO. The efficiency of the inverted organic solar cells was found to depend on the coating speed of the IGZO films, which was attributed to the change in the concentration of surface OH groups. Compared to organic solar cells of conventional structure using PBDTTT-C-T: [70]PCBM as active laye...

Highly efficient organic light emitting diodes based on solution/evaporation hybrid process

The solution/evaporation hybrid processed organic light emitting devices composed of newly developed host material CzDBS, green PG-02 dopant, and orange PO-01-TB and PO-06 dopants are studied. Orange, green and two-peak white light emitting devices were fabricated by using spin coating of HIL, HTL and emission layers followed by thermal evaporation of ETL and cathode. The orange devices achieved efficacies of 26.9 cd/A and 14.6 lm/W at the brightness of 1538 nits. The green devices, on the other hand, achieved efficacies of 31.3 cd/A and 19.7 lm/W at the brightness of 1590 nits. The two-peak white devices, composed of blue FIrpic and orange PO-01-TB, achieved efficacies of 36.9 cd/A and 18.4 lm/W at the brightness of 1150 nits.

Recent progress on solution processable small molecules for organic light-emitting diodes in ITRI

A series of novel thieno[3,2-c]pyridine-based RGBY phosphorescent Ir complexes have been synthesized and characterized. Solution-processable double-layered OLEDs fabricated with theses materials as the light-emitting layer exhibit high efficiencies. The monochromatic large-area of 40 x 83 mm2 Yellow and Green OLEDs have also been demonstrated.