Organic solar cells (OSCs) are promising renewable energy sources for replacing fossil fuels. The power conversion efficiency (PCE) of OSCs has increased based on tremendous effort in material and device engineering. Still, the stability of OSC, such as long lifetime, negative temperature coefficient, must be enhanced for commercialization. In this study, we investigated OSC performance at a high operating temperature near 300–420 K, which are typical temperature regions in photovoltaic applications, with a different hole-extraction layer (HEL). The metal oxide-based HEL, MoO3, exhibited stable operating properties with a PCE drop rate of −0.13%/°C, as compared to polymeric HEL, PEDOT:PSS (−0.20%/°C). This performance reduction of polymeric HEL originated from the degradation of the interface in contact with PEDOT:PSS, as compared to the robust inorganic metal oxide HEL.

In this study, we present optical simulation versus real fabricated device results in the micro-cavity red top-emitting organic light emitting diodes (TEOLEDs). The optical simulation results indicate that the two kinds of possible emissive layer (EML) positions exist in the second order micro-cavity effect and each EMLs could emit the similar radiance with near National Television System Committee (NTSC) color coordinate. Expected current efficiency and external quantum efficiency by the optical simulation toward the surface normal in the red tandem TEOLED are 98.8 cd/A and 22.6% for two EMLs, while fabricated device shows 95.8 cd/A and 26.5%, respectively.

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flexibility. In recent times, several prototypes of the flexible display based on OLED have been reported. [2][3][4] However, there are still some issues related to the fabrication of flexible OLEDs. Among the main concerns, securing transparent conducting electrode (TCE) with high mechanical flexibility as well as durability and good thermal stability are the most important issue. Generally, widely used TCE, Indiumtin-oxide (ITO) is not suitable for flexible display applications despite high transparency and conductivity due to its high rigidity. Therefore, to replace ITO, various types of flexible TCEs such as conducting metal oxide, [5][6][7] metal nanowire, [8,9] metal mesh, [10,11] carbon nanotube, [12,13] graphene, [14,15] and conducting polymers [16,17] have been reported.An ultrathin metal layer or sputter coinage metal, especially silver (Ag), with a thickness of about 10-14 nm is one of the noteworthy and alternative flexible TCEs because of its high transparency and low sheet resistance. The high ductility of the ultrathin metal layer makes it a flexible electrode to ensure high durability against the mechanical deformations. Moreover, it has a simple fabrication process which includes thermal deposition at room temperature using a fine metal mask without any patterning process for instance photo lithography. However, sole ultrathin Ag film with low resistivity and good uniformity cannot be formed accurately due to the Ag agglomeration, which induced by the stronger cohesion force between Ag clusters than the adhesion force of metal-substrate interface. [18][19][20][21] Typically, the Ag agglomeration aggravates the sheet resistance property owing to incomplete electrical path connection, as a result, low transmittance at the thickness of Ag with sufficiently low sheet resistance. To overcome this, metal oxide-based dielectricmetal-dielectric multilayer structures have been largely developed for optoelectronic devices. [22][23][24][25][26][27] Normally, the metal oxide-based binding/seed layer can reduce the coalescence between Ag clusters by increasing the interface adhesion force according to the bonding formation between Ag and oxygen. [21] However, metal oxide, especially molybdenum This paper reports an efficient, thermally stable, and high-performance flexible multilayer transparent conducting electrode (TCE) by sandwiching an ultrathin Ag layer between a thermally evaporated small-molecule organic wetting inducer, 1,4-bis(2-phenyl-1,10-phenanthrolin-4-yl)benzene and an organic antireflective capping layer, 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile for flexible organic light-emitting diodes (OLEDs). This TCE demonstrates a high transmittance of about 81.34% at 550 nm and very low sheet resistance of 9.51 Ω sq −1 with excellent thermal stability under high-temperature (100 °C for 72 h) conditions. These properties arise from the synergistic effect of coordinate bonding between the nitrogen of the phenanthroline moiety and the Ag atom which leads to a smooth and uniform Ag surface and the o...

In this paper, we report bipolar host materials, 6- (2,6-diphenylpyrimidin-4-yl)-12,12-dimethyl-6,12,12′-trihydroindeno[1,2-b]carbazole (DPICz1) and 6-(2,6-diphenyl-pyrimidin-4-yl)-12,12-dimethyl-6,12,12′trihydroindeno[1,2-b]carbazole (DPICz2), with indenocarbazole moiety as a hole-transporting unit and pyrimidine moiety as an electron-transporting unit for highly efficient green phosphorescent organic light-emitting diodes. The synthesized materials show excellent electro-optical properties. Similarly, it also exhibits outstanding thermal and morphological stability due to high glass transition temperature (T g ) of 161 °C and decomposition temperature (T d ) of 327−401 °C. Fabricated green phosphorescent organic light-emitting diode shows excellent current and power efficiency of 77.8 cd/A and 62.8 lm/W as well as almost ideal external quantum efficiency of 22.3% at the brightness of 1000 cd/m 2 .