Organic Light-Emitting diodes (OLEDs) are extremely sensitive to water vapour and oxygen, which causes rapid degradation. Epoxy and cover glass with large amount of desiccant are commonly applied to encapsulate bottom...Organic Light-Emitting diodes (OLEDs) are extremely sensitive to water vapour and oxygen, which causes rapid degradation. Epoxy and cover glass with large amount of desiccant are commonly applied to encapsulate bottom emitting OLEDs which is not a viable option for flexible as well as top emitting OLEDs. This paper reports a completely organic encapsulating layer consisting of four periods of alternate stacks of two organic materials with different morphologies deposited by simple vacuum thermal evaporation technique. Standard green OLED structures with and without encapsulation were fabricated and investigated using structural, optical and electrical studies. Moreover, the encapsulation presented being organic is safe for underlying organic layers in OLEDs and is ultrathin, transparent and without any cover glass and desiccant, ensuring its application in flexible and top emitting OLEDs.展开更多
Recently developed lead-free double perovskite nanocrystals(NCs)have been proposed for the possible application in solutionprocessed optoelectronic devices.However,the optoelectronic applications of double perovskite ...Recently developed lead-free double perovskite nanocrystals(NCs)have been proposed for the possible application in solutionprocessed optoelectronic devices.However,the optoelectronic applications of double perovskite NCs have been hampered due to the structural and chemical instability in the presence of polar molecules.Here,we report a facile strategy for the synthesis and purification of Cs_(2)AgBiBr_(6)double perovskite NCs that remained stable even after washing with polar solvent.This is realized with our efficient colloidal route to synthesize Cs_(2)AgBiBr_(6)NCs that involve stable and strongly coordinated precursor such as silvertrioctyl phosphine complex together with bismuth neodecanoate,which leads to a significantly improved chemical and colloidal stability.Using layer-by-layer solid-state ligand exchange technique,a compact and crack-free thin film of Cs_(2)AgBiBr_(6)NCs were fabricated.Finally,perovskite solar cells consisting of Cs_(2)AgBiBr_(6)as an absorber layer were fabricated and tested.展开更多
We have synthesized and characterized a new electroluminescent material, [8-hydroxyquinoline] bis[2,2＇bipyridine] aluminum. A solution of this material Al（Bpy）2q in toluene showed absorption maxima at 380 nm,which ...We have synthesized and characterized a new electroluminescent material, [8-hydroxyquinoline] bis[2,2＇bipyridine] aluminum. A solution of this material Al（Bpy）2q in toluene showed absorption maxima at 380 nm,which was attributed to the moderate energy（ π–π＊） transitions of the aromatic rings. The photoluminescence spectrum of Al（Bpy）_2q in the toluene solution showed a peak at 518 nm. This material shows thermal stability up to300 ℃. The structure of the device is ITO/F4-TCNQ（1 nm）/α-NPD（35 nm）/Al（Bpy）2q（35 nm）/ BCP（6 nm）/Alq3（28 nm）/Li F（1 nm）/Al（150 nm）. This device exhibited a luminescence peak at 515 nm（CIE coordinates, xD0.32,yD0.49）. The maximum luminescence of the device was 214 cd/m^2 at 21 V. The maximum current efficiency of OLED was 0.12 cd/A at 13 V and the maximum power efficiency was 0.03 lm/W at 10 V.展开更多
A new electroluminescent material tris- [5-choloro-8-hydroxyquinoline] aluminum has been synthesized and characterized. Solution of this material AI（5-Clq）3 in toluene showed absorption maxima at 385 nm which was at...A new electroluminescent material tris- [5-choloro-8-hydroxyquinoline] aluminum has been synthesized and characterized. Solution of this material AI（5-Clq）3 in toluene showed absorption maxima at 385 nm which was attributed to the moderate energy （π-π＊） transitions of the aromatic rings. The photoluminescence spectrum of AI（5-Clq）3 in toluene solution showed a peak at 522 nm. This material shows thermal stability up to 400 ℃. The structure of the device is ITO/0.4 wt%F4-TCNQ doped α-NPD （35 nm） / AI（5-Clq）3 （30 nm） / BCP （6 nm）/ Alq3 （30 nm） / LiF （1 nm） / A1 （150 nm）. This device exhibited a luminescence peak at 585 nm （CIE coordinates, x = 0.39, y = 0.50）. The maximum luminescence of the device was 920 Cd/m2 at 25 V. The maximum current efficiency of OLED was 0.27 Cd/A at 20 V and maximum power efficiency was 0.04 lm/W at 18 V.展开更多
Producing environmentally stable monolayers and few-layers of hafnium disulphide （HfS2） with a high yield to reveal its unlocked electronic and optoelectronic applications is still a challenge. HfS2 is a layered two...Producing environmentally stable monolayers and few-layers of hafnium disulphide （HfS2） with a high yield to reveal its unlocked electronic and optoelectronic applications is still a challenge. HfS2 is a layered two-dimensional material of group-IV transition metal dichalcogenides. For the first time, we demonstrate a simple and cost-effective method to grow layered belt-like nanocrystals of HfS2 with a notably large interlayer spacing followed by their chemical exfoliation. Various microscopic and spectroscopic techniques confirm that these as-grown crystals exfoliate into single or multiple layers in a few minutes using solvent assisted ultrasonification method in N-cyclohexyl-2- pyrrolidone. The exfoliated nanosheets of HfS2 exhibit an indirect bandgap of 1.3 eV with high stability against surface degradation. Furthermore, we demonstrate that these nanosheets hold potential for electronic applications by fabricating a field-effect transistor based on few-layered HfS2, exhibiting a field-effect mobility of 0.95 cm2/（V.s） with a high on/off current modulation ratio of 10,000 in ambient conditions. The method is scalable and has a potential significance for both academic and industrial purposes.展开更多
文摘Organic Light-Emitting diodes (OLEDs) are extremely sensitive to water vapour and oxygen, which causes rapid degradation. Epoxy and cover glass with large amount of desiccant are commonly applied to encapsulate bottom emitting OLEDs which is not a viable option for flexible as well as top emitting OLEDs. This paper reports a completely organic encapsulating layer consisting of four periods of alternate stacks of two organic materials with different morphologies deposited by simple vacuum thermal evaporation technique. Standard green OLED structures with and without encapsulation were fabricated and investigated using structural, optical and electrical studies. Moreover, the encapsulation presented being organic is safe for underlying organic layers in OLEDs and is ultrathin, transparent and without any cover glass and desiccant, ensuring its application in flexible and top emitting OLEDs.
文摘Recently developed lead-free double perovskite nanocrystals(NCs)have been proposed for the possible application in solutionprocessed optoelectronic devices.However,the optoelectronic applications of double perovskite NCs have been hampered due to the structural and chemical instability in the presence of polar molecules.Here,we report a facile strategy for the synthesis and purification of Cs_(2)AgBiBr_(6)double perovskite NCs that remained stable even after washing with polar solvent.This is realized with our efficient colloidal route to synthesize Cs_(2)AgBiBr_(6)NCs that involve stable and strongly coordinated precursor such as silvertrioctyl phosphine complex together with bismuth neodecanoate,which leads to a significantly improved chemical and colloidal stability.Using layer-by-layer solid-state ligand exchange technique,a compact and crack-free thin film of Cs_(2)AgBiBr_(6)NCs were fabricated.Finally,perovskite solar cells consisting of Cs_(2)AgBiBr_(6)as an absorber layer were fabricated and tested.
文摘We have synthesized and characterized a new electroluminescent material, [8-hydroxyquinoline] bis[2,2＇bipyridine] aluminum. A solution of this material Al（Bpy）2q in toluene showed absorption maxima at 380 nm,which was attributed to the moderate energy（ π–π＊） transitions of the aromatic rings. The photoluminescence spectrum of Al（Bpy）_2q in the toluene solution showed a peak at 518 nm. This material shows thermal stability up to300 ℃. The structure of the device is ITO/F4-TCNQ（1 nm）/α-NPD（35 nm）/Al（Bpy）2q（35 nm）/ BCP（6 nm）/Alq3（28 nm）/Li F（1 nm）/Al（150 nm）. This device exhibited a luminescence peak at 515 nm（CIE coordinates, xD0.32,yD0.49）. The maximum luminescence of the device was 214 cd/m^2 at 21 V. The maximum current efficiency of OLED was 0.12 cd/A at 13 V and the maximum power efficiency was 0.03 lm/W at 10 V.
文摘A new electroluminescent material tris- [5-choloro-8-hydroxyquinoline] aluminum has been synthesized and characterized. Solution of this material AI（5-Clq）3 in toluene showed absorption maxima at 385 nm which was attributed to the moderate energy （π-π＊） transitions of the aromatic rings. The photoluminescence spectrum of AI（5-Clq）3 in toluene solution showed a peak at 522 nm. This material shows thermal stability up to 400 ℃. The structure of the device is ITO/0.4 wt%F4-TCNQ doped α-NPD （35 nm） / AI（5-Clq）3 （30 nm） / BCP （6 nm）/ Alq3 （30 nm） / LiF （1 nm） / A1 （150 nm）. This device exhibited a luminescence peak at 585 nm （CIE coordinates, x = 0.39, y = 0.50）. The maximum luminescence of the device was 920 Cd/m2 at 25 V. The maximum current efficiency of OLED was 0.27 Cd/A at 20 V and maximum power efficiency was 0.04 lm/W at 18 V.
文摘Producing environmentally stable monolayers and few-layers of hafnium disulphide （HfS2） with a high yield to reveal its unlocked electronic and optoelectronic applications is still a challenge. HfS2 is a layered two-dimensional material of group-IV transition metal dichalcogenides. For the first time, we demonstrate a simple and cost-effective method to grow layered belt-like nanocrystals of HfS2 with a notably large interlayer spacing followed by their chemical exfoliation. Various microscopic and spectroscopic techniques confirm that these as-grown crystals exfoliate into single or multiple layers in a few minutes using solvent assisted ultrasonification method in N-cyclohexyl-2- pyrrolidone. The exfoliated nanosheets of HfS2 exhibit an indirect bandgap of 1.3 eV with high stability against surface degradation. Furthermore, we demonstrate that these nanosheets hold potential for electronic applications by fabricating a field-effect transistor based on few-layered HfS2, exhibiting a field-effect mobility of 0.95 cm2/（V.s） with a high on/off current modulation ratio of 10,000 in ambient conditions. The method is scalable and has a potential significance for both academic and industrial purposes.
