A solution-processed zinc oxide (ZnO) thin film as an electron collection layer for polymer solar cells (PSCs) with an inverted device structure was investigated. Power conversion efficiencies (PCEs) of PSCs made with...A solution-processed zinc oxide (ZnO) thin film as an electron collection layer for polymer solar cells (PSCs) with an inverted device structure was investigated. Power conversion efficiencies (PCEs) of PSCs made with a blend of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) are 3.50% and 1.21% for PSCs with and without the ZnO thin film, respectively. Light intensity dependence of the photocurrent and the capacitance-voltage measurement demonstrate that the increased PCEs are due to the restriction of the strong bimolecular recombination in the interface when a thin ZnO layer is inserted between the polymer active layer and the ITO electrode. These results demonstrate that the ZnO thin film plays an important role in the performance of PSCs with an inverted device structure.展开更多
Efficient white-polymer-light-emitting devices (WPLEDs) have been fabricated with a single emitting layer containing a hole-transporting host polymer,poly(N-vinylcarbzole),and an electron-transporting auxiliary,1,3-bi...Efficient white-polymer-light-emitting devices (WPLEDs) have been fabricated with a single emitting layer containing a hole-transporting host polymer,poly(N-vinylcarbzole),and an electron-transporting auxiliary,1,3-bis[(4-tert-butylphenyl)-1,3,4-oxadiazolyl]-phenylene,codoped with two phosphorescent dyes:Iridium(III)bis (2-(4,6-difluorophenyl)-pyridinato-N,C2') picolinate (FIrpic) and home-made Ir-G2 for blue and red emission,respectively.With the structure of ITO/PEDOT:PSS 4083(40 nm)/emission layer(80 nm)/Ba(4 nm)/Al(120 nm),the device showed a maximal luminous efficiency (LE) of 13.5 cd A-1(corresponding to an external quantum efficiency (EQE) of 6.8%),and a peak power efficiency (PE) of 6.5 lm W-1 at 6.0 V.Meanwhile,the device exhibited pure white emission with Commission Internationale de l'Eclairage (CIE) coordinates of (0.34,0.35) at a current density of 12 mA cm-2,which is very close to the equi-energy white point with CIE coordinates of (0.33,0.33).The device performance can be further optimized when more balanced hole/electron injection is achieved by incorporating a lower conducting type anode buffer layer (PEDOT:PSS) and incorporating poly[(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorenene)-alt-2,7-(9,9-dioctyfluorene)] (PFN) as an electron injection layer at the cathode.The optimized device showed an LE of 24.6 cd A-1 (with an EQE of 14.1%),while the peak power efficiency reached 12.66 lm W-1.Moreover,the WPLEDs showed good electroluminescence (EL) stability over a wide range of operating current density and luminance.展开更多
A new silole monomer with two 4-（N,N-dimethylamino）phenyl substitutions on silicon atom as designed and synthesized. Three copolymers PF-N-HPS1, PF-N-HPS10 and PF-N-HPS20 were then obtained by copolymerizations of 2...A new silole monomer with two 4-（N,N-dimethylamino）phenyl substitutions on silicon atom as designed and synthesized. Three copolymers PF-N-HPS1, PF-N-HPS10 and PF-N-HPS20 were then obtained by copolymerizations of 2,7-fluorene deriva- tives with the silole monomer at feed ratios of 1%, 10%, and 20%. Their UV-vis absorption, electrochemical, photolumines- cent, and electroluminescent （EL） properties were investigated. PF-N-HPS possessed HOMO levels of -5.25-5.58 eV, and showed green emissions. Using PF-N-HPS as the emissive layer, three different polymer light-emitting diodes were fabricated as device A with ITO/PEDOT/PF-N-HPS/A1, device B with ITO/PEDOT/PF-N-HPS/Ba/A1, and device C with ITO/PEDOT/ PF-N-HPS/TPBI/Ba/A1. For the device A, PF-N-HPS only showed very low EL efficiency of 0.06-0.33 cd/A, indicating that the A1 cathode could not inject electron efficiently to the emissive polymers containing the 4-（N,N-dimethylamino）phenyl groups. For the device B, low work function Ba supplied better electron injections, and the EL efficiency could be improved to 0.85-1.44 cd/A. TPBI with a deep HOMO level of -6.2 eV could enhance electron transport and hole blocking. Thus modi- fied recombinations and largely elevated EL efficiency of 4.56-7.96 cd/A were achieved for the device C. The separation of the emissive layer and metal cathode with the TPBI layer may also suppress exciton quenching at the cathode interface.展开更多
A novel three-component copolymer (PFDP), derived from 9,9-dihexylfluorene, diketopyrrolopyrrole( DPP), and 10-octylphenothiazine, was synthesized through palladium-catalyzed Suzuki polycondensation in good yields. PF...A novel three-component copolymer (PFDP), derived from 9,9-dihexylfluorene, diketopyrrolopyrrole( DPP), and 10-octylphenothiazine, was synthesized through palladium-catalyzed Suzuki polycondensation in good yields. PFDP possessed moderate molecular weight and polydispersity, well-defined structure, and excellent thermal properties with an onset decomposition temperature at 357°C. PFDP in thin film exhibited red photoluminescence from DPP chromophore exclusively, with a peak at 602 nm. Electron-rich phenothiazine units sighificantly improved the injection and transport of holes by incorporating into polymer backbone. Light-emitting device was fabricated in the ITO/PEDOT: PSS/PVK/ polymer/Ba/Al configuration using PFDP as the emitting layer. The device based on PFDP showed red emission [CIE coordinate value (0.62, 0.38)] that was close to the standard red (0.66, 0.34). The results on electroluminescent performance revealed that PFDP may be a promising candidate for the red emitter with a maximum brightness of 259 cd/m2 and a maximum external quantum efficiency of 0.25%.展开更多
基金the Joint Researh Fund for Overseas Chinese Scholars, and the National Natural Science Foundation of China (50828301)the NSFC (50990065, U0634003, and 60937001)+1 种基金MOST (2009CB603601)973 project (2009CB623604)
文摘A solution-processed zinc oxide (ZnO) thin film as an electron collection layer for polymer solar cells (PSCs) with an inverted device structure was investigated. Power conversion efficiencies (PCEs) of PSCs made with a blend of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) are 3.50% and 1.21% for PSCs with and without the ZnO thin film, respectively. Light intensity dependence of the photocurrent and the capacitance-voltage measurement demonstrate that the increased PCEs are due to the restriction of the strong bimolecular recombination in the interface when a thin ZnO layer is inserted between the polymer active layer and the ITO electrode. These results demonstrate that the ZnO thin film plays an important role in the performance of PSCs with an inverted device structure.
基金Fund of Ministry of Education of China (20090172120012)the National Basic Research Program of Chima (2009CB623602)+4 种基金the National Natural Science Foundation of China (60906032)the Fundamental Research Funds for the Central Universities for the financial support. Wong W.-Y. thanks the Hong Kong Research Grants Council (HKBU202709)the University Grants Committee of HKSAR,China (AoE/P-03/08)Hong Kong Baptist University (FRG2/08-09/111)the Croucher Foundation for the Croucher Senior Research Fellowship
文摘Efficient white-polymer-light-emitting devices (WPLEDs) have been fabricated with a single emitting layer containing a hole-transporting host polymer,poly(N-vinylcarbzole),and an electron-transporting auxiliary,1,3-bis[(4-tert-butylphenyl)-1,3,4-oxadiazolyl]-phenylene,codoped with two phosphorescent dyes:Iridium(III)bis (2-(4,6-difluorophenyl)-pyridinato-N,C2') picolinate (FIrpic) and home-made Ir-G2 for blue and red emission,respectively.With the structure of ITO/PEDOT:PSS 4083(40 nm)/emission layer(80 nm)/Ba(4 nm)/Al(120 nm),the device showed a maximal luminous efficiency (LE) of 13.5 cd A-1(corresponding to an external quantum efficiency (EQE) of 6.8%),and a peak power efficiency (PE) of 6.5 lm W-1 at 6.0 V.Meanwhile,the device exhibited pure white emission with Commission Internationale de l'Eclairage (CIE) coordinates of (0.34,0.35) at a current density of 12 mA cm-2,which is very close to the equi-energy white point with CIE coordinates of (0.33,0.33).The device performance can be further optimized when more balanced hole/electron injection is achieved by incorporating a lower conducting type anode buffer layer (PEDOT:PSS) and incorporating poly[(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorenene)-alt-2,7-(9,9-dioctyfluorene)] (PFN) as an electron injection layer at the cathode.The optimized device showed an LE of 24.6 cd A-1 (with an EQE of 14.1%),while the peak power efficiency reached 12.66 lm W-1.Moreover,the WPLEDs showed good electroluminescence (EL) stability over a wide range of operating current density and luminance.
基金supported by the National Natural Science Foundation of China (21225418,51003080)the National Basic Research Program of China (2013CB834705)+2 种基金the Youth Science Plan for Light of the Morning Sun of Wuhan City (201271031385)State Key Laboratory of Luminescent Materials and Devices (2012-09)Natural Science Foundation of Hubei Province (2012FFB04705)
文摘A new silole monomer with two 4-（N,N-dimethylamino）phenyl substitutions on silicon atom as designed and synthesized. Three copolymers PF-N-HPS1, PF-N-HPS10 and PF-N-HPS20 were then obtained by copolymerizations of 2,7-fluorene deriva- tives with the silole monomer at feed ratios of 1%, 10%, and 20%. Their UV-vis absorption, electrochemical, photolumines- cent, and electroluminescent （EL） properties were investigated. PF-N-HPS possessed HOMO levels of -5.25-5.58 eV, and showed green emissions. Using PF-N-HPS as the emissive layer, three different polymer light-emitting diodes were fabricated as device A with ITO/PEDOT/PF-N-HPS/A1, device B with ITO/PEDOT/PF-N-HPS/Ba/A1, and device C with ITO/PEDOT/ PF-N-HPS/TPBI/Ba/A1. For the device A, PF-N-HPS only showed very low EL efficiency of 0.06-0.33 cd/A, indicating that the A1 cathode could not inject electron efficiently to the emissive polymers containing the 4-（N,N-dimethylamino）phenyl groups. For the device B, low work function Ba supplied better electron injections, and the EL efficiency could be improved to 0.85-1.44 cd/A. TPBI with a deep HOMO level of -6.2 eV could enhance electron transport and hole blocking. Thus modi- fied recombinations and largely elevated EL efficiency of 4.56-7.96 cd/A were achieved for the device C. The separation of the emissive layer and metal cathode with the TPBI layer may also suppress exciton quenching at the cathode interface.
基金Supported by the National Natural Science Foundation of China (Grant No. 20872038)Science and Technology Planning Project of Guangdong Province, China (Grant No. 2007A010500011)Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20060561024)
文摘A novel three-component copolymer (PFDP), derived from 9,9-dihexylfluorene, diketopyrrolopyrrole( DPP), and 10-octylphenothiazine, was synthesized through palladium-catalyzed Suzuki polycondensation in good yields. PFDP possessed moderate molecular weight and polydispersity, well-defined structure, and excellent thermal properties with an onset decomposition temperature at 357°C. PFDP in thin film exhibited red photoluminescence from DPP chromophore exclusively, with a peak at 602 nm. Electron-rich phenothiazine units sighificantly improved the injection and transport of holes by incorporating into polymer backbone. Light-emitting device was fabricated in the ITO/PEDOT: PSS/PVK/ polymer/Ba/Al configuration using PFDP as the emitting layer. The device based on PFDP showed red emission [CIE coordinate value (0.62, 0.38)] that was close to the standard red (0.66, 0.34). The results on electroluminescent performance revealed that PFDP may be a promising candidate for the red emitter with a maximum brightness of 259 cd/m2 and a maximum external quantum efficiency of 0.25%.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.90201031&50573024)Key Project of Science and Technology,Ministry of Education(Grant No.104208)the State 973 Project(Grant No.2002CB613405).
