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1.
Novel red phosphorescent emitter bis(2,3-diphenylquinolinato-N,C2’) iridium(acetylacetonate) [(23dpq)2Ir(acac)] has been synthesised and fully characterized. A highly efficient red organic light-emitting diode was fabricated by using (23dpq)2Ir(acac) as an emitter, in which (23dpq)2Ir(acac) was synthesised from a well-designed ligand-2,3-diphenylquinoline. Electroluminescent device with a configuration of ITO/2-TNATA/NPB/BAlq:(23dpq)2Ir(acac)/AlQ3/LiF/Al was fabricated. The device using (23dpq)2Ir(acac) as a dopant showed pure-red emission with 1931 CIE (Commission International de L’Eclairage) chromaticity coordinates x = 0.66, y = 0.34. 相似文献
2.
Several new iridium complexes with substituted 2-phenylthiazoles as the cyclometalated ligands have been synthesized and characterized to try to investigate the effect of the size of the π system and substituent groups on physical properties. The complexes have the general structure of (C∧N)2Ir(acac), where the C∧N are 2-phenylthiazole (ptz), 2-(4-methylphenyl)thiazole (mptz), 2-(4-ethylphenyl)thiazole (eptz). The absorption, emission, cyclic voltammetry and thermostability of the complexes were systematically investigated. The experimental results revealed that the maximum emission wavelength in CH2Cl2 at room temperature are in the range 542-547 nm, which is blue shift than that of the known iridium(III) bis(2-phenylbenzothiazolato-N,C2′) acetyl acetonate (bt)2Ir(acac) due to decreasing the size of the π system in the benzothiazole portion of 2-phenylbenzothiazole ligand. 相似文献
3.
Synthesis and characterization of four iridium(III) complexes containing 2-benzo[b]thiophen-2-yl-pyridine based ligands are reported. The absorption, emission, electrochemistry, and thermostability of the complexes were systematically investigated. The (btmp)2Ir(acac) (btmp = 2-benzo[b]thiophen-2-yl-4-methyl-pyridyl, acac = acetyl acetone) was characterized using X-ray crystallography. Calculation on the electronic ground state for (btmp)2Ir(acac) was carried out using B3LYP density functional theory, HOMO levels are a mixture of Ir and btmp ligand orbitals, while the LUMO is predominantly btmp ligand based. Introduction of substituents (CH3, CF3) into pyridyl ring in a typical red emitter (btp)2Ir(acac) leads to a marked decrease in the sublimation temperature, which is more suitable for OLEDs process. Electrochemical studies showed that (btmp)2Ir(acac) has a slightly lower oxidation potential, but (btfmp)2Ir(acac), (btfmp)2Ir(dbm), and (btfmp)2Ir(pic) (btfmp = 2-benzo[b]thiophen-2-yl-5-trifluoromethyl-pyridine, dbm = dibenzoylmethane, pic = 2-picolinic acid) containing CF3 group are much difficult to oxidate than (btp)2Ir(acac). The emission characteristics of these complexes can be tuned by either changing the substituents and their position on 2-benzo[b]thiophen-2-yl-pyridine or using different monoanionic ligands, showing emission λmax values from 604 to 638 nm in CH2Cl2 solution at room temperature. 相似文献
4.
George Kakavelakis Ioannis Vangelidis Amelie Heuer‐Jungemann Antonios G. Kanaras Elefterios Lidorikis Emmanuel Stratakis Emmanuel Kymakis 《Liver Transplantation》2016,6(2)
A universal strategy for efficient light trapping through the incorporation of gold nanorods on the electron transport layer (rear) of organic photovoltaic devices is demonstrated. Utilizing the photons that are transmitted through the active layer of a bulk heterojunction photovoltaic device and would otherwise be lost, a significant enhancement in power conversion efficiency (PCE) of poly[N‐9′‐heptadecanyl‐2,7‐carbazole‐alt‐5,5‐(4′,7′‐di‐2‐thienyl‐2′,1′,3′‐benzothiadiazole)]:phenyl‐C71‐butyric acid methyl ester (PCDTBT:PC71BM) and poly[[4,8‐bis[(2‐ethylhexyl)oxy]benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl][3‐fluoro‐2‐[(2‐ethylhexyl)carbonyl]thieno[3,4‐b] thiophenediyl]] (PTB7):PC71BM by ≈13% and ≈8%, respectively. PCEs over 8% are reported for devices based on the PTB7:PC71BM blend. A comprehensive optical and electrical characterization of our devices to clarify the influence of gold nanorods on exciton generation, dissociation, charge recombination, and transport inside the thin film devices is performed. By correlating the experimental data with detailed numerical simulations, the near‐field and far‐field scattering effects are separated of gold nanorods (Au NRs), and confidently attribute part of the performance enhancement to the enhanced absorption caused by backscattering. While, a secondary contribution from the Au NRs that partially protrude inside the active layer and exhibit strong near‐fields due to localized surface plasmon resonance effects is also observed but is minor in magnitude. Furthermore, another important contribution to the enhanced performance is electrical in nature and comes from the increased charge collection probability. 相似文献
5.
This paper focuses on an optical study of a Tb3+/Bi3+‐doped and Sm3+/La3+‐ doped Ca2Al2SiO7 phosphor synthesized using combustion methods. Here, Ca2Al2SiO7:Sm3+ showed a red emission band under visible light excitation but, when it co‐doped with La3+ ions, the emission intensity was further enhanced. Ca2Al2SiO7:Tb3+ shows the characteristic green emission band under near‐ultraviolet light excitation wavelengths, co‐doping with Bi3+ ions produced enhanced photoluminescence intensity with better colour tunable properties. The phosphor exhibited better phase purity and crystallinity, confirmed by X‐ray diffraction. Binding energies of Ca(2p), Al(2p), Si(2p), O(1s) were studied using X‐ray photoelectron spectroscopy. The reported phosphor may be a promising visible light excited red phosphor for light‐emitting diodes and energy conversion devices. 相似文献
6.
Shuangling Lou Junsheng Yu Jincheng Qian Yadong Jiang Qing Zhang Hongjie Xu Limei Sun 《Luminescence》2008,23(6):424-428
The photo‐physical properties of 6,6′‐(9H‐fluoren‐9,9‐diyl)bis(2,3‐bis(9,9‐dihexyl‐9H‐fluoren‐2‐yl)quinoxaline) (BFLBBFLYQ) and its blend doped with N′‐biphenyl‐N,N′‐bis‐(3‐methylphenyl)‐1,1′‐biphenyl‐4,4′‐diamine (TPD) were investigated. The absorption, photoluminescence (PL) and electroluminescence (EL) properties of pristine BFLBBFLYQ and blend in solution and spin‐coated film are outlined, including a discussion of charge‐transfer (CT) exciplex emission of BFLBBFLYQ:TPD blend in the solid state. The luminescent properties of BFLBBFLYQ films using different deposition processes were studied. It was found that the low‐energy emission bands at 530–570 nm appeared in the PL spectra of BFLBBFLYQ evaporated films in ultra‐high vacuum. Also, the low‐energy band was the exclusive emission in the EL spectra of BFLBBFLYQ films. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
7.
Doping‐Free Asymmetrical Silicon Heterocontact Achieved by Integrating Conjugated Molecules for High Efficient Solar Cell
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Jiawei Liu Yujin Ji Yuqiang Liu Zhouhui Xia Yujie Han Youyong Li Baoquan Sun 《Liver Transplantation》2017,7(19)
Organic conjugated molecule/silicon (Si) heterojunction has been widely investigated to build up an asymmetrical heterocontact for efficient photovoltaics. However, it is still unclear how the organic molecular structures can affect their electronic coupling interaction with Si. Here, two widely explored electron acceptors of poly{[N,N′‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene)} (N2200) and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) are used to build up asymmetrical Si heterocontact to investigate their electronic coupling interaction. It is found that PCBM displays different electronic coupling with Si from N2200, which is ascribed to their various physical distance with Si based on a systematic and detailed density functional theory calculation. Organic layer incorporation not only suppresses the surface charge recombination velocity but also leads to an Ohmic contact between Si and Al. Therefore, a doping‐free organic/Si heterojunction photovoltaic with a power conversion efficiency of 14.9% is achieved with PCBM layer. This work discloses a key factor affecting organic/Si electronic coupling interaction, which helps build up high quality Si heterocontact for solar cells and other optoelectronic devices. Furthermore, the simplified heterocontact achieved by a low temperature, solution processed, and lithography‐free steps has a dramatic improvement on conventional diffusion doped‐silicon one at high temperature. 相似文献
8.
Three ortho-metallated iridium complexes whose emission maxima fall in different regions of the electromagnetic spectrum were bound in either Nafion or poly(9-vinylcarbazole) and their electrogenerated chemiluminescence (ECL) reported. The reaction of F(Ir)pic [bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)-iridium III] with the oxidative-reductive co-reactant tri-n-propylamine (TPrA) resulted in ECL when the iridium complex was bound in Nafion. No significant ECL was observed for (btp)(2)Ir(acac) (bis[2,(2'-benzothienyl)-pyridinato-N,C3'](acetylacetonate)Ir(III)), and Ir(ppy)(3) (where ppy = 2-phenylpyridine) under these conditions. However, all three compounds displayed ECL with TPrA when bound in poly(9-vinylcarbazole). 相似文献
9.
Several iridium complexes containing trifluoromethyl-substituted phenyl pyridine based ligands have been synthesized and characterized to try to investigate the effect of trifluoromethyl group and its position on physical properties. The complexes have the general structure of (C-N)2Ir(LX), where the C-N are 2-phenylpyridine (ppy), 2-(3,5-bis-trifluoromethylphenyl)pyridine (fmppy), 2-(3,5-bis-trifluoromethylphenyl)-4-methylpyridine (fmpmpy), 2-(3,5-bis-trifluoromethylphenyl)-5-trifluoromethylpyridine (tfmppy) and the LX are 2-picolinic acid (pic) and acetylacetonate (acac). The (tfmppy)2Ir(pic) was characterized using X-ray crystallography. The absorption, emission, and thermostability of the complexes were systematically investigated. Introduction of CF3 substituents into 2-phenylpyridine in (ppy)2Ir(pic) lead to some decrease in the sublimation temperature, which is more suitable to devices fabrication. The experimental results revealed that the emissive colors of these complexes could be finely tuned by suitable incorporation of trifluoromethyl substituents on the 2-phenylpyridine ligand, obtaining bright green-blue emission λmax values from 471 to 489 nm in CH2Cl2 solution at room temperature, with high solution quantum efficiencies ranging from 0.37 to 1.89 relative to Ir(ppy)3. 相似文献
10.
Hamed Azimi Alessia Senes Markus C. Scharber Kurt Hingerl Christoph J. Brabec 《Liver Transplantation》2011,1(6):1162-1168
Charge transport and recombination are studied for organic solar cells fabricated using blends of polymer poly[(4,4′‐bis(2‐ethylhexyl)dithieno[3,2‐b:2′,3′‐d]silole)‐2,6‐diyl‐alt‐(4,7‐bis(2‐thienyl)‐2,1,3‐benzothiadiazole)‐5,5′‐diyl] (Si‐PCPDTBT) with [6,6]‐phenyl‐C61‐butyric acid methyl ester (mono‐PCBM) and the bis‐adduct analogue of mono‐PCBM (bis‐PCBM). The photocurrent of Si‐PCPDTBT:bis‐PCBM devices shows a strong square root dependence on the effective applied voltage. From the relationship between the photocurrent and the light intensity, we found that the square‐root dependence of the photocurrent is governed by the mobility‐lifetime (μτ) product of charge carriers while space‐charge field effects are insignificant. The fill factor (FF) and short circuit current density (Jsc) of bis‐PCBM solar cells show a considerable increase with temperature as compared to mono‐PCBM solar cells. SCLC analysis of single carrier devices proofs that the mobility of both electrons and holes is significantly lowered when replacing mono‐PCBM with bis‐PCBM. The increased recombination in Si‐PCPDTBT:bis‐PCBM solar cells is therefore attributed to the low carrier mobilities, as the transient photovoltage measurements show that the carrier lifetime of devices are not significantly altered by using bis‐PCBM instead of mono‐PCBM. 相似文献
11.
Germanium‐ and Silicon‐Substituted Donor–Acceptor Type Copolymers: Effect of the Bridging Heteroatom on Molecular Packing and Photovoltaic Device Performance
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Jong Soo Kim Zhuping Fei Sebastian Wood David T. James Myungsun Sim Kilwon Cho Martin J. Heeney Ji‐Seon Kim 《Liver Transplantation》2014,4(18)
The effects of heteroatom substitution from a silicon atom to a germanium atom in donor‐acceptor type low band gap copolymers, poly[(4,4′‐bis(2‐ethylhexyl)dithieno[3,2‐b:2′,3′‐d]silole)‐2,6‐diyl‐alt‐(2,1,3‐benzothiadiazole)‐4,7‐diyl] (PSiBTBT) and poly[(4,4′‐bis(2‐ethylhexyl)dithieno[3,2‐b:2′,3′‐d]germole)‐2,6‐diyl‐alt‐(2,1,3‐benzothiadiazole)‐4,7‐diyl] (PGeBTBT), are studied. The optoelectronic and charge transport properties of these polymers are investigated with a particular focus on their use for organic photovoltaic (OPV) devices in blends with phenyl‐C70‐butyric acid methyl ester (PC70BM). It is found that the longer C‐Ge bond length, in comparison to C‐Si, modifies the molecular conformation and leads to a more planar chain conformation in PGeBTBT than PSiBTBT. This increase in molecular planarity leads to enhanced crystallinity and an increased preference for a face‐on backbone orientation, thus leading to higher charge carrier mobility in the diode configuration. These results provide important insight into the impact of the heavy atom substitution on the molecular packing and device performance of polymers based on the poly[2,6‐(4,4‐bis‐(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b;3,4‐b]‐dithiophene)‐alt‐4,7‐(2,1,3‐benzothiadiazole) (PCPDTBT) backbone. 相似文献
12.
Andreas Distler Tobias Sauermann Hans‐Joachim Egelhaaf Sheila Rodman Dave Waller Kap‐Soo Cheon Mike Lee Dirk M. Guldi 《Liver Transplantation》2014,4(1)
Increasing the lifetime of polymer based organic solar cells is still a major challenge. Here, the photostability of bulk heterojunction solar cells based on the polymer poly[4,4′‐bis(2‐ethylhexyl)dithieno[3,2‐b:2′,3′‐d]silole)‐2,6‐diyl‐alt‐[2,5‐bis(3‐tetradecylthiophen‐2‐yl)thiazole[5,4‐d]thiazole)‐1,8‐diyl] (PDTSTzTz) and the fullerene [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC60BM) under inert atmosphere is investigated. Correlation of electrical measurements on complete devices and UV‐vis absorption measurements as well as high‐performance liquid chromatography (HPLC) analysis on the active materials reveals that photodimerization of PC60BM is responsible for the observed degradation. Simulation of the electrical device parameters shows that this dimerization results in a significant reduction of the charge carrier mobility. Both the dimerization and the associated device performance loss turn out to be reversible upon annealing. BisPC60BM, the bis‐substituted analog of PC60BM, is shown to be resistant towards light exposure, which in turn enables the manufacture of photostable PDTSTzTz:bisPC60BM solar cells. 相似文献
13.
Sequential Processing for Organic Photovoltaics: Design Rules for Morphology Control by Tailored Semi‐Orthogonal Solvent Blends
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Jordan C. Aguirre Steven A. Hawks Amy S. Ferreira Patrick Yee Selvam Subramaniyan Samson A. Jenekhe Sarah H. Tolbert Benjamin J. Schwartz 《Liver Transplantation》2015,5(11)
Design rules are presented for significantly expanding sequential processing (SqP) into previously inaccessible polymer:fullerene systems by tailoring binary solvent blends for fullerene deposition. Starting with a base solvent that has high fullerene solubility, 2‐chlorophenol (2‐CP), ellipsometry‐based swelling experiments are used to investigate different co‐solvents for the fullerene‐casting solution. By tuning the Flory‐Huggins χ parameter of the 2‐CP/co‐solvent blend, it is possible to optimally swell the polymer of interest for fullerene interdiffusion without dissolution of the polymer underlayer. In this way solar cell power conversion efficiencies are obtained for the PTB7 (poly[(4,8‐bis[(2‐ethylhexyl)oxy]benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl)(3‐fluoro‐2‐[(2‐ethylhexyl)carbonyl]thieno[3,4‐b]thiophenediyl)]) and PC61BM (phenyl‐C61‐butyric acid methyl ester) materials combination that match those of blend‐cast films. Both semicrystalline (e.g., P3HT (poly(3‐hexylthiophene‐2,5‐diyl)) and entirely amorphous (e.g., PSDTTT (poly[(4,8‐di(2‐butyloxy)benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl)‐alt‐(2,5‐bis(4,4′‐bis(2‐octyl)dithieno[3,2‐b:2′3′‐d]silole‐2,6‐diyl)thiazolo[5,4‐d]thiazole)]) conjugated polymers can be processed into highly efficient photovoltaic devices using the solvent‐blend SqP design rules. Grazing‐incidence wide‐angle x‐ray diffraction experiments confirm that proper choice of the fullerene casting co‐solvent yields well‐ordered interdispersed bulk heterojunction (BHJ) morphologies without the need for subsequent thermal annealing or the use of trace solvent additives (e.g., diiodooctane). The results open SqP to polymer/fullerene systems that are currently incompatible with traditional methods of device fabrication, and make BHJ morphology control a more tractable problem. 相似文献
14.
Hong Duc Pham Thu Trang Do Jinhyun Kim Cecile Charbonneau Sergei Manzhos Krishna Feron Wing Chung Tsoi James R. Durrant Sagar M. Jain Prashant Sonar 《Liver Transplantation》2018,8(16)
In this report, highly efficient and humidity‐resistant perovskite solar cells (PSCs) using two new small molecule hole transporting materials (HTM) made from a cost‐effective precursor anthanthrone (ANT) dye, namely, 4,10‐bis(1,2‐dihydroacenaphthylen‐5‐yl)‐6,12‐bis(octyloxy)‐6,12‐dihydronaphtho[7,8,1,2,3‐nopqr]tetraphene (ACE‐ANT‐ACE) and 4,4′‐(6,12‐bis(octyloxy)‐6,12‐dihydronaphtho[7,8,1,2,3‐nopqr]tetraphene‐4,10‐diyl)bis(N,N‐bis(4‐methoxyphenyl)aniline) (TPA‐ANT‐TPA) are presented. The newly developed HTMs are systematically compared with the conventional 2,2′,7,7′‐tetrakis(N,N′‐di‐p‐methoxyphenylamino)‐9,9′‐spirbiuorene (Spiro‐OMeTAD). ACE‐ANT‐ACE and TPA‐ANT‐TPA are used as a dopant‐free HTM in mesoscopic TiO2/CH3NH3PbI3/HTM solid‐state PSCs, and the performance as well as stability are compared with Spiro‐OMeTAD‐based PSCs. After extensive optimization of the metal oxide scaffold and device processing conditions, dopant‐free novel TPA‐ANT‐TPA HTM‐based PSC devices achieve a maximum power conversion efficiency (PCE) of 17.5% with negligible hysteresis. An impressive current of 21 mA cm?2 is also confirmed from photocurrent density with a higher fill factor of 0.79. The obtained PCE of 17.5% utilizing TPA‐ANT‐TPA is higher performance than the devices prepared using doped Spiro‐OMeTAD (16.8%) as hole transport layer at 1 sun condition. It is found that doping of LiTFSI salt increases hygroscopic characteristics in Spiro‐OMeTAD; this leads to the fast degradation of solar cells. While, solar cells prepared using undoped TPA‐ANT‐TPA show dewetting and improved stability. Additionally, the new HTMs form a fully homogeneous and completely covering thin film on the surface of the active light absorbing perovskite layers that acts as a protective coating for underlying perovskite films. This breakthrough paves the way for development of new inexpensive, more stable, and highly efficient ANT core based lower cost HTMs for cost‐effective, conventional, and printable PSCs. 相似文献
15.
Zinc sulfide (ZnS) doped with transition metal has been used as phosphor for various optoelectronic applications. In the present report, ZnS:Mn doped and ZnS:Mn,Ni co‐doped were prepared using chemical co‐precipitation method using polyvinyl pyrolidone as a surfactant. The structural studies were carried out using an X‐ray diffraction technique; optical studies have been performed using ultraviolet–visible light absorption and photoluminescence (PL) spectroscopy. The presences of functional groups were confirmed using Fourier transform infrared spectroscopy. The X‐ray diffraction study and Reitveld analysis confirms the formation of cubic phase with crystalline size 2–3 nm for undoped and doped ZnS nanoparticles. A novel and enhanced luminescence characteristic have been observed in PL spectra. The luminescence intensity of Mn,Ni co‐doped ZnS in the blue region is much higher of that of ZnS. The PL results indicate that the doping of Ni creates shallow trap states or luminescence centres in the forbidden energy gap, which quenches the Mn states emission. Concentration quenching has been observed in Mn‐doped ZnS nanoparticles. From CIE coordinates, it is seen that the yellow and blue light emission of ZnS:Mn,Ni co‐doped nanophosphor may be a promising candidate for display devices and phosphor converted light‐emitting diode applications. 相似文献
16.
Efficient blue organic light‐emitting diodes using N2,N2,N11,N11,5,6,7,8‐octaphenyltriphenylene‐2,11‐diamine derivatives
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Young Seok Kim Su Jin Jeong Hyun Woo Lee Jwajin Kim Song Eun Lee Young Kwan Kim Seung Soo Yoon 《Luminescence》2016,31(4):1031-1036
In this study, we have synthesized phenyl‐substituted triphenylene derivatives, using the Diels–Alder reaction and the Buchwald–Hartwig reaction. To investigate electroluminescence properties of these materials, multilayer organic light‐emitting diode (OLED) devices were fabricated with a structure of indium–tin–oxide (ITO) (180 nm)/4,4′‐bis(N‐(1‐naphthyl)‐N‐phenylamino)biphenyl (NPB) (50 nm)/blue‐emitting materials (1–3) (30 nm)/bathophenanthroline (Bphen) (35 nm)/lithium quinolate (Liq) (2 nm)/Al (100 nm). A device using N2,N2,N11,N11,5,6,7‐heptaphenyltriphenylene‐2,11‐diamine (2) exhibited efficient blue emission with luminous, power, and external quantum efficiencies of 0.92 cd/A, 0.67 lm/W, and 1.17% at 20 mA/cm2, respectively. The Commission International de L'Éclairage coordinates of this device were (x = 0.15, y = 0.09) at 6.0 V. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
17.
Y2O3:Tm3+ and Li+ co‐doped Y2O3:Tm3+ nanopowders were synthesized using the solution combustion method for possible application in ultraviolet (UV) light dosimetry. X‐ray diffraction revealed the crystallite sizes to be in the range 21–44 nm and 30–121 nm using the Scherrer equation and the W‐H plot relationship, respectively. Field emission scanning electron microscopy confirmed that, after co‐doping with 4 mol% concentration of Li+, the particles were spherical in nature with an average size of ~30 nm. Fourier transformed infrared spectroscopy results showed bands at wavenumbers of 556, 1499, 1704, 2342, 2358, 2973, 3433, and 3610 cm?1 that corresponded to the stretching and bending vibrations of Y–O, C=O and O–H. Thermoluminescence (TL) glow peaks for Y2O3:Tm3+ nanophosphors observed at 399 and 590 K were attributed to oxygen defects caused using UV irradiation. These oxygen defects firstly resulted in an increased prominent peak TL intensity for up to 270 min of irradiation and then a decrease. This was attributed to the presence of oxygen defect clusters that caused a reduction in recombination centres. The Li+ co‐doped sample showed peaks at 356, 430, and 583 K and its intensity sublinearly increased up to 90 min and then thereafter decreased. The TL trapping parameters were calculated using computerized glow curve deconvolution methods. The Li+ co‐doped sample exhibited less fading and high trap density under the UV radiation. 相似文献
18.
Kai Zhang Baobing Fan Ruoxi Xia Xiang Liu Zhicheng Hu Honggang Gu Shiyuan Liu Hin‐Lap Yip Lei Ying Fei Huang Yong Cao 《Liver Transplantation》2018,8(15)
In the field of organic solar cells (OSCs), tandem structure devices exhibit very attractive advantages for improving power conversion efficiency (PCE). In addition to the well researched novel pair of active layers in different subcells, the construction of interconnecting layer (ICL) also plays a critical role in achieving high performance tandem devices. In this work, a new way of achieving environmentally friendly solvent processed polymeric ICL by adopting poly[(9,9‐bis(3′‐(N,N‐dimethylamino)propyl)‐2,7‐fluorene)‐alt‐5,5′‐bis(2,2′‐thiophene)‐2,6‐naphthalene‐1,4,5,8‐tetracaboxylic‐N,N′‐di(2‐ethylhexyl)imide] (PNDIT‐F3N) blended with poly(ethyleneimine) (PEI) as the electron transport layer (ETL) and PEDOT:PSS as the hole transport layer is reported. It is found that the modification ability of PNDIT‐F3N on PEDOT can be linearly tuned by the incorporation of PEI, which offers the opportunity to study the charge recombination behavior in ICL. At last, tandem OSC with highest PCE of 12.6% is achieved, which is one of the best tandem OSCs reported till now. These results offer a new selection for constructing efficient ICL in high performance tandem OSCs and guide the way of design new ETL materials for ICL construction, and may even be integrated in future printed flexible large area module device fabrication with the advantages of environmentally friendly solvent processing and thickness insensitivity. 相似文献
19.
Significance of Average Domain Purity and Mixed Domains on the Photovoltaic Performance of High‐Efficiency Solution‐Processed Small‐Molecule BHJ Solar Cells
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Subhrangsu Mukherjee Christopher M. Proctor Guillermo C. Bazan Thuc‐Quyen Nguyen Harald Ade 《Liver Transplantation》2015,5(21)
Whereas the role of molecularly mixed domains in organic photovoltaic devices for charge generation is extensively discussed in the literature, the impact on charge recombination and thus fill factor is largely unexplored. Here, a combination of soft X‐ray techniques enables the quantification of phases at multiple length scales to reveal their role regarding charge recombination in a highly efficient solution processed small molecule system 7,7′‐(4,4‐bis(2‐ethylhexyl)‐4H‐silolo[3,2‐b:4,5‐b′]dithiophene‐2,6‐diyl)bis(6‐fluoro‐4‐(5′‐hexyl‐[2,2′‐bithiophen]‐5‐yl)benzo[c][1,2,5]thiadiazole) (p‐DTS(FBTTh2)2) . A quantitative (linear) relationship between the average composition variations and the device fill‐factor is observed. The results establish the complex interrelationship between average phase purity, domain size, and structural order and highlight the requirement of achieving sufficient phase purities to diminish bimolecular and geminate recombination in solution processed small molecule solar cells. 相似文献
20.
Frequency up‐conversion (UC) emission from the Nd3+‐Yb3+/Nd3+‐Yb3+‐Li+ co‐doped gadolinium oxide (Gd2O3) phosphors prepared by the solution combustion technique in the visible range have been studied by using 980 nm near infrared (NIR) laser diode excitation. The crystalline structure and formation of the cubic phase has been confirmed with the help of X‐ray diffraction (XRD) studies. XRD peak shifts have been found towards the lower diffraction angle side in the case of the Nd3+‐Yb3+‐Li+ co‐doped phosphors. Surface morphology and particle size information have been observed by using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analysis. Down‐conversion emission study under 351 nm excitation in the visible region for the Nd3+‐Yb3+/Nd3+‐Yb3+‐Li+ co‐doped phosphors has been performed. The UC emission bands lying in the green and red region arising from the Nd3+ ions have been enhanced by ~260 times, ~113 times due to incorporation of Li+ ions in the Nd3+‐Yb3+ co‐doped phosphors. Photometric characterization has been done for the Nd3+‐Yb3+/Nd3+‐Yb3+‐Li+ co‐doped phosphors. The present study suggests the capability of the synthesized phosphors in near‐infrared (NIR) to visible upconverter and luminescent device applications. 相似文献