Co-reporter:Zifeng Zhao;Gang Yu;Qiaowen Chang;Xiaochen Liu;Yang Liu;Liding Wang;Zuqiang Bian;Weiping Liu;Chunhui Huang
Journal of Materials Chemistry C 2017 vol. 5(Issue 29) pp:7344-7351
Publication Date(Web):2017/07/27
DOI:10.1039/C7TC01594A
A high triplet energy level (ET) and balanced carrier mobility are critical factors for host materials in efficient blue phosphorescent organic light-emitting diodes (PHOLEDs). Herein, we report a facile synthesis of four compounds, dicarbazolylphenylphosphine (DCPP), dicarbazolylphenylphosphine oxide (DCPPO), tricarbazolylphosphine (TCP), and tricarbazolylphosphine oxide (TCPO), and their application as host materials in a classic blue phosphorescent emitter bis[2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato)iridium(III) (FIrpic). The four compounds show a high ET of up to 3.0 eV and tunable mobilities. We fabricated four OLEDs with a device structure of ITO/MoO3 (1 nm)/N,N′-dicarbazolyl-3,5-benzene (mCP):MoO3 (20 wt%, 10 nm)/mCP (30 nm)/Host:FIrpic (7 wt%, 20 nm)/1,3,5-tri(m-pyrid-3-yl-phenyl) benzene (TmPyPB, 40 nm)/LiF (1 nm)/Al (100 nm), all of which display maximum external quantum efficiencies (EQEs) exceeding 20%. The DCPPO-based device reaches the highest EQE of 27.5%, the maximum luminance of 14 070 cd m−2, and the lowest efficiency roll-off of 22.2% from 1 to 10 mA cm−2, which is among the best-performing FIrpic-based PHOLEDs without using any light extraction method.
Co-reporter:Ziran Zhao;Feidan Gu;Yunlong Li;Weihai Sun;Senyun Ye;Haixia Rao;Zuqiang Bian;Chunhui Huang
Advanced Science 2017 Volume 4(Issue 11) pp:
Publication Date(Web):2017/11/01
DOI:10.1002/advs.201700204
AbstractIn this work, a fully tin-based, mixed-organic-cation perovskite absorber (FA)x(MA)1−xSnI3 (FA = NH2CH = NH2+, MA = CH3NH3+) for lead-free perovskite solar cells (PSCs) with inverted structure is presented. By optimizing the ratio of FA and MA cations, a maximum power conversion efficiency of 8.12% is achieved for the (FA)0.75(MA)0.25SnI3-based device along with a high open-circuit voltage of 0.61 V, which originates from improved perovskite film morphology and inhibits recombination process in the device. The cation-mixing approach proves to be a facile method for the efficiency enhancement of tin-based PSCs.
Co-reporter:Yu Tan;Zifeng Zhao;Liang Shang;Yang Liu;Chen Wei;Jiayi Li;Huibo Wei;Zuqiang Bian;Chunhui Huang
Journal of Materials Chemistry C 2017 vol. 5(Issue 45) pp:11901-11909
Publication Date(Web):2017/11/23
DOI:10.1039/C7TC04089J
Tremendous efforts have been devoted to developing efficient deep-blue organic light-emitting diodes (OLEDs), but deep-blue OLEDs with high external quantum efficiency (EQE) and CIEy < 0.10 (Commission Internationale de L’éclairage (CIE)), especially matching the National Television System Committee (NTSC) standard blue CIE (x, y) coordinates of (0.14, 0.08), are still limited. Herein, we report the synthesis, photophysical properties, thermostability and electrochemical characterization of two phenanthroimidazole/carbazole-based compounds (CBPMCN and CPBPMCN). Single X-ray crystal data of CPBPMCN indicate that it adopts a severely twisted structure, resulting in a low degree of intermolecular π–π stacking, which is appropriate to be employed as a nondoped deep-blue emitter. Nondoped devices based on CPBPMCN exhibited deep-blue electroluminescence (EL) with CIE coordinates of (0.15, 0.08), which is extremely close to the NTSC standard blue. Meanwhile, the devices showed impressively high EQEmax up to 5.80% with relatively small efficiency roll-off.
Co-reporter:Yang Liu;Ge Zhan;Peiyu Fang;Zuqiang Bian;Chunhui Huang
Journal of Materials Chemistry C 2017 vol. 5(Issue 47) pp:12547-12552
Publication Date(Web):2017/12/07
DOI:10.1039/C7TC04634K
A big step towards manipulating organic triplet harvesting has been taken in three N-benzoyl-carbazole regioisomeric microcrystals (L-(p,m,o)Br) which consist of a –Br group at the para (p)/meta (m)/ortho (o) positions of the phenyl ring, respectively. The manipulation is demonstrated by blue thermally activated delayed fluorescence (TADF) emission in L-pBr, blue and yellow dual room temperature phosphorescence (RTP) emissions with different lifetimes in L-mBr, and ultralong yellow RTP in L-oBr. The effect of the –Br group was verified in molecular excited electronic structures and packing modes upon crystallization. Single crystal analysis and theoretical calculations reveal that exciton structures in the L-(p,m,o)Br dimers are strongly influenced by the bromine substitution positions, leading to different ways to harvest triplet excitons. As a simple and feasible strategy, taking advantage of the substitution position effect is promising in the manipulation of organic triplet excitons to achieve multifarious applications based on triplet exciton properties.
Co-reporter:Ziran Zhao;Weihai Sun;Yunlong Li;Senyun Ye;Haixia Rao;Feidan Gu;Zuqiang Bian;Chunhui Huang
Journal of Materials Chemistry A 2017 vol. 5(Issue 10) pp:4756-4773
Publication Date(Web):2017/03/07
DOI:10.1039/C6TA10305G
Organo-metal halide perovskite solar cells have shown great potential for application in photovoltaics with their high power conversion efficiency. For the future commercialisation of perovskite solar cells, it is crucial to simplify their device structures while maintaining their efficiency. In this review, we discuss the recent progress in the simplification of device structures for low-cost, high-efficiency perovskite solar cells after briefly reviewing the evolution of the device structures of perovskite solar cells.
Co-reporter:Weihai Sun, Yunlong Li, Senyun Ye, Haixia Rao, Weibo Yan, Haitao Peng, Yu Li, Zhiwei Liu, Shufeng Wang, Zhijian Chen, Lixin Xiao, Zuqiang Bian and Chunhui Huang
Nanoscale 2016 vol. 8(Issue 20) pp:10806-10813
Publication Date(Web):26 Apr 2016
DOI:10.1039/C6NR01927G
During the past several years, methylammonium lead halide perovskites have been widely investigated as light absorbers for thin-film photovoltaic cells. Among the various device architectures, the inverted planar heterojunction perovskite solar cells have attracted special attention for their relatively simple fabrication and high efficiencies. Although promising efficiencies have been obtained in the inverted planar geometry based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) sulfonic acid (PEDOT:PSS) as the hole transport material (HTM), the hydrophilicity of the PEDOT:PSS is a critical factor for long-term stability. In this paper, a CuOx hole transport layer from a facile solution-processed method was introduced into the inverted planar heterojunction perovskite solar cells. After the optimization of the devices, a champion PCE of 17.1% was obtained with an open circuit voltage (Voc) of 0.99 V, a short-circuit current (Jsc) of 23.2 mA cm−2 and a fill factor (FF) of 74.4%. Furthermore, the unencapsulated device cooperating with the CuOx film exhibited superior performance in the stability test, compared to the device involving the PEDOT:PSS layer, indicating that CuOx could be a promising HTM for replacing PEDOT:PSS in inverted planar heterojunction perovskite solar cells.
Co-reporter:Haixia Rao, Weihai Sun, Senyun Ye, Weibo Yan, Yunlong Li, Haitao Peng, Zhiwei Liu, Zuqiang Bian, and Chunhui Huang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 12) pp:7800
Publication Date(Web):March 11, 2016
DOI:10.1021/acsami.5b12776
Organic–inorganic hybrid perovskite solar cells (PSCs) have drawn worldwide intense research in recent years. Herein, we have first applied another p-type inorganic hole-selective contact material, CuS nanoparticles (CuS NPs), in an inverted planar heterojunction (PHJ) perovskite solar cell. The CuS NP-modification of indium tin oxide (ITO) has successfully tuned the surface work function from 4.9 to 5.1 eV but not affect the surface roughness and transmittance, which can effectively reduce the interfacial carrier injection barrier and facilitate high hole extraction efficiency between the perovskite and ITO layers. After optimization, the maximum power conversion efficiency (PCE) has been over 16% with low J–V hysteresis and excellent stability. Therefore, the low-cost solution-processed and stable CuS NPs would be an alternative interfacial modification material for industrial production in perovskite solar cells.Keywords: CuS; hole-selective contact; nanoparticles; perovskite; solar cell
Co-reporter:Xiaoyue Li, Juanye Zhang, Feng Wei, Xiaochen Liu, Zhiwei Liu, Zuqiang Bian and Chunhui Huang
CrystEngComm 2016 vol. 18(Issue 23) pp:4388-4394
Publication Date(Web):16 Mar 2016
DOI:10.1039/C5CE02533H
Three new bisphosphine ligands, 4-phenyl-1,2-bis(diphenylphosphino)benzene (Ph-dppb), 4-pyrrolyl-1,2-bis(diphenylphosphino)benzene (Pr-dppb), and 4,5-dimethoxyl-1,2-bis(diphenylphosphino)benzene (OMe-dppb), were synthesized to coordinate with cuprous iodide (CuI), and compared with 1,2-bis(diphenylphosphino)benzene (dppb). Single crystal X-ray diffraction and elemental analysis experiments indicate that three binuclear CuI complexes with formulae of [Cu(μ2-I)Ph-dppb]2, [Cu(μ2-I)Pr-dppb]2, and [Cu(μ2-I)OMe-dppb]2 were obtained, which are the same as the reference complex [Cu(μ2-I)dppb]2. The three complexes showed a maximum emission band (λmax) in the range of 484–535 nm which varies in the electron effect of the substituted groups (i.e. methoxy, pyrrolyl, phenyl) on [Cu(μ2-I)dppb]2, and in high photoluminescence quantum yield (PLQY) from 53 to 90% in the solid state. Furthermore, the complexes [Cu(μ2-I)Ph-dppb]2 and [Cu(μ2-I)Pr-dppb]2 exhibited a thermal decomposition temperature exceeding 380 °C. The high PLQY and excellent thermal stability of these CuI complexes imply their great potential application as efficient emitters in organic light-emitting diodes (OLEDs).
Co-reporter:Xiaochen Liu, Jacky Qiu, Zhende Wang, Yang Liu, Zhibin Wang, Zhiwei Liu, Zuqiang Bian, Zhenghong Lu, Chunhui Huang
Organic Electronics 2016 Volume 37() pp:421-427
Publication Date(Web):October 2016
DOI:10.1016/j.orgel.2016.07.021
•High efficiency Cu(I) complex based OLEDs were achieved by a codeposition method.•Different reactant structures, reaction ratios, and deposition rates were compared to investigate in situ reaction.•Optimal chemical reaction condition and device architecture play critical roles in high efficiency OLEDs.Cu(I) complexes are considered as idea emitters in organic light-emitting diodes (OLEDs) due to their low cost and theoretical high internal quantum efficiency, which are two important issues have to be concerned for OLEDs commercialization. However, most Cu(I) complexes are unstable toward sublimation and hence not amenable to the vacuum deposition method typically used to fabricate OLEDs. To solve this problem, a codeposition route that involves codeposition of CuI and pyridine derivative has been proposed to synthesis Cu(I) complex emitter in situ. Since chemical reactions were conducted in a vacuum chamber, we systematically studied the effect of reactant chemical structure, reaction ratio, and deposition rate on the in situ synthesized Cu(I) complex and its application as an emitter in OLEDs. With an optimal chemical reaction condition, the device showed a high external quantum efficiency (EQE) up to 14.2% at a brightness of 100 cd/m2, corresponding to a current and power efficiency of 45.2 cd/A and 33.3 lm/W, respectively. The performance is comparable to those efficient OLEDs with iridium complex emitter, while using a CuI dopant that having only one ten-thousandth of price to bis(2-phenylpyridine) (acetylacetonate)iridium.
Co-reporter:Yang Liu, Ge Zhan, Zhi-Wei Liu, Zu-Qiang Bian, Chun-Hui Huang
Chinese Chemical Letters 2016 Volume 27(Issue 8) pp:1231-1240
Publication Date(Web):August 2016
DOI:10.1016/j.cclet.2016.06.029
Room-temperature phosphorescence (RTP) materials have attracted great attention due to their involvement of excited triplet states and comparatively long decay lifetimes. In this short review, recent progress on enhancement of RTP from purely organic materials is summarized. According to the mechanism of phosphorescence emission, two principles are discussed to construct efficient RTP materials: one is promoting intersystem crossing (ISC) efficiency by using aromatic carbonyl, heavy-atom, or/and heterocycle/heteroatom containing compounds; the other is suppressing intramolecular motion and intermolecular collision which can quench excited triplet states, including embedding phosphors into polymers and packing them tightly in crystals. With aforementioned strategies, RTP from purely organic materials was achieved both in fluid and rigid media.In this short review, two strategies for designing efficient room-temperature phosphorescence (RTP) materials are discussed: one is promoting intersystem crossing (ISC) efficiency and the other is suppressing molecular motion. Recent progress on RTP from purely organic materials is classified and summarized.
Co-reporter:Haixia Rao, Senyun Ye, Weihai Sun, Weibo Yan, Yunlong Li, Haitao Peng, Zhiwei Liu, Zuqiang Bian, Yongfang Li, Chunhui Huang
Nano Energy 2016 Volume 27() pp:51-57
Publication Date(Web):September 2016
DOI:10.1016/j.nanoen.2016.06.044
•A novel Cl doping process was first introduced in the PSCs.•The Cl incorporation forms (MAPbI3-xClx and MAPbCl3) were studied.•The Cl doping effect (morphology, carrier mobility and Rrec) were investigated.•A record PCE of 19.0% of the inorganic hole conductor-based PSCs was achieved.Hybrid organic-inorganic perovskite solar cells (PSCs) have exhibited huge potential for commercial application due to their various advantages such as high performance, flexible and so on. The inorganic hole conductor-based inverted planar PSCs are particularly significant on account of low cost and high stability. Here, we have successfully improved the power conversion efficiency (PCE) of this type of PSCs to 19.0% with CuOx as hole conductor and hybrid CH3NH3PbI3−xClx perovskite as light absorber prepared by a novel Cl doping process based on a modified one-step fast deposition-crystallization method. This novel Cl doping process has proven to be a crucially effective procedure for enhancing the device performance due to the remarkable morphology and hole mobility improvement of the perovskite film, conspicuous intrinsic defects reduction in the film and prominent increase of the device recombination resistance.
Co-reporter:Senyun Ye, Weihai Sun, Yunlong Li, Weibo Yan, Haitao Peng, Zuqiang Bian, Zhiwei Liu, and Chunhui Huang
Nano Letters 2015 Volume 15(Issue 6) pp:3723-3728
Publication Date(Web):May 4, 2015
DOI:10.1021/acs.nanolett.5b00116
Although inorganic hole-transport materials usually possess high chemical stability, hole mobility, and low cost, the efficiency of most of inorganic hole conductor-based perovskite solar cells is still much lower than that of the traditional organic hole conductor-based cells. Here, we have successfully fabricated high quality CH3NH3PbI3 films on top of a CuSCN layer by utilizing a one-step fast deposition-crystallization method, which have lower surface roughness and smaller interface contact resistance between the perovskite layer and the selective contacts in comparison with the films prepared by a conventional two-step sequential deposition process. The average efficiency of the CuSCN-based inverted planar CH3NH3PbI3 solar cells has been improved to 15.6% with a highest PCE of 16.6%, which is comparable to that of the traditional organic hole conductor-based cells, and may promote wider application of the inexpensive inorganic materials in perovskite solar cells.
Co-reporter:Yunlong Li;Weihai Sun;Weibo Yan;Senyun Ye;Haitao Peng;Zuqiang Bian;Chunhui Huang
Advanced Functional Materials 2015 Volume 25( Issue 30) pp:4867-4873
Publication Date(Web):
DOI:10.1002/adfm.201501289
Solution-processable hybrid perovskite solar cells are a new member of next generation photovoltaics. In the present work, a low-temperature two-step dipping method is proposed for the fabrication of CH3NH3PbI3-xClx perovskite films on the indium tin oxide glass/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) substrate. The bandgaps of the CH3NH3PbI3-xClx perovskite films are tuned in the range between 1.54 and 1.59 eV by adjusting the PbCl2 mole fraction (nCl/(nCl + nI)) in the initial mixed precursor solution from 0.10 to 0.40. The maximum chlorine mole fraction measured by a unique potentiometric titration method in the produced CH3NH3PbI3-xClx films can be up to 0.220 ± 0.020 (x = 0.660 ± 0.060), which is much higher than that produced by a one-step spin-coating method (0.056 ± 0.015, x = 0.17 ± 0.04). The corresponding solar cell with the CH3NH3PbI2.34±0.06Cl0.66±0.06 perovskite film sandwiched between PEDOT:PSS and C60 layers exhibits a power conversion efficiency as high as 14.5%. Meanwhile, the open-circuit potential (Voc) of the device reaches 1.11 V, which is the highest Voc reported in the perovskite solar cells fabricated on PEDOT:PSS so far.
Co-reporter:Tianchi Ni, Xiaochen Liu, Tao Zhang, Hongliang Bao, Ge Zhan, Nan Jiang, Jianqiang Wang, Zhiwei Liu, Zuqiang Bian, Zhenghong Lu and Chunhui Huang
Journal of Materials Chemistry A 2015 vol. 3(Issue 22) pp:5835-5843
Publication Date(Web):01 May 2015
DOI:10.1039/C5TC00727E
Inexpensive materials made of abundant natural resources such as CuI complexes are essential to sustain the development of organic light emitting diode (OLED) technology for mass market applications such as solid-state illumination. CuI complexes, however, mostly are neither soluble nor stable toward sublimation, which is a road block for the development of efficient CuI complex based OLEDs using traditional methods of synthesis, sublimation and vacuum evaporation. In this work, two isoquinolyl carbazole (CIQ) compounds 9-(8-(carbazol-9-yl)isoquinolin-5-yl)-carbazole (DCIQ) and 9-(4-(5-(4-(carbazol-9-yl)phenyl)isoquinolin-8-yl)phenyl)-carbazole (DCDPIQ) were synthesized to codeposition with copper iodide (CuI) to form red emissive dimeric CuI complex doped film in situ, which could be utilized directly as the emissive layer (EML) in OLEDs. After a systematic study of the two compounds and their codeposited CuI:CIQ films, as well as optimizing the CuI doping concentration, it is found that red OLEDs can be achieved, showing a maximum emission band, an external quantum efficiency (EQE), a luminance of 643 nm, 3.5%, 3290 cd m−2 for DCIQ, and 635 nm, 3.6%, 853 cd m−2 for DCDPIQ, respectively.
Co-reporter:Xiaochen Liu;Tao Zhang;Tianchi Ni;Nan Jiang;Zuqiang Bian;Zhenghong Lu;Chunhui Huang
Advanced Functional Materials 2014 Volume 24( Issue 34) pp:5385-5392
Publication Date(Web):
DOI:10.1002/adfm.201400685
Four compounds 4-[3,6-di(carbazol-9-yl)carbazol-9-yl]isoquinoline (TCIQ), 3-[3,6-di(carbazol-9-yl)carbazol-9-yl]pyridine (TCPy), 4-(carbazol-9-yl)isoquinoline (4CIQ), and 3-(carbazol-9-yl)pyridine (CPy) containing pyridyl or isoquinolyl were designed and synthesized to co-deposition with copper iodide (CuI) to form luminescent Cu(I) complex doped film in situ, which could be utilized as the emissive layer in organic light-emitting diodes (OLEDs). It is found that simple tri-layered yellow and white OLEDs can be achieved by co-depositing CuI and TCIQ with tuning ratios. The compound TCIQ serves a dual role as both a ligand for forming the emissive Cu(I) complex and as a host matrix for the formed emitter in yellow OLEDs, and a third role as a blue emitter in white OLEDs.
Co-reporter:Feng Wei, Jacky Qiu, Xiaochen Liu, Jianqiang Wang, Huibo Wei, Zhibin Wang, Zhiwei Liu, Zuqiang Bian, Zhenghong Lu, Yongliang Zhao and Chunhui Huang
Journal of Materials Chemistry A 2014 vol. 2(Issue 31) pp:6333-6341
Publication Date(Web):30 Jun 2014
DOI:10.1039/C4TC00410H
Inexpensive and eco-friendly luminescent Cu(I) complexes are ideal phosphorescent emitters for high efficiency organic light-emitting diodes (OLEDs). A series of pyrazinyl carbazole (CPz) compounds were designed and synthesized to obtain efficient luminescent Cu(I) complexes through reaction with CuI using a vacuum codeposition method. Based on photophysical studies of the CPz compounds and their codeposited CuI–CPz films, the compound 9-(3-(6-(carbazol-9-yl)pyrazin-2-yl)phenyl)-carbazole (CPzPC) with CuI was chosen as the emissive layer for OLED fabrication, where the emitter was identified as Cu2(μ-I)2(CPzPC)4 on the basis of X-ray absorption spectroscopy. After optimizing the device architecture and material selection including the CuI doping concentration and hole transporting layer, an efficient orange-red emitting OLED with a maximum emission band, an external quantum efficiency (EQE), and a luminance of 590 nm, 6.6% and 8619 cd m−2 (10 V), respectively, was achieved.
Co-reporter:Feng Wei, Tao Zhang, Xiaochen Liu, Xiaoyue Li, Nan Jiang, Zhiwei Liu, Zuqiang Bian, Yongliang Zhao, Zhenghong Lu, Chunhui Huang
Organic Electronics 2014 Volume 15(Issue 11) pp:3292-3297
Publication Date(Web):November 2014
DOI:10.1016/j.orgel.2014.09.004
•A high efficiency nondoped OLED with a CuI complex emitter was obtained.•The nondoped OLED is better than the one with a IrIII complex emissive layer.•The nondoped OLED is better than the one with a doped CuI complex emissive layer.•A series of reference films and single carrier devices were fabricated and studied.In CuI complex based organic light emitting diodes (OLEDs) a host matrix is traditionally thought to be required to achieve high efficiency. Herein, it is found that the device ITO/MoO3 (1 nm)/4,4′-N,N′-dicarbazole-biphenyl (CBP, 35 nm)/[Cu(μ-I)dppb]2 (dppb = 1,2-bis[diphenylphosphino]benzene, 20 nm)/1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene (TPBi, 65 nm)/LiF (1 nm)/Al (100 nm) with a vacuum thermal evaporated nondoped CuI complex emissive layer (EML) showed external quantum efficiency and current efficiency of 8.0% and 24.3 cd/A at a brightness of 100 cd/m2, respectively, which are comparable to the maximum efficiencies reported in an optimized doped OLED with the same emitter, higher efficiency than the OLED with a [Cu(μ-I)dppb]2:CBP EML, and much higher efficiencies than the nondoped OLED with a bis(2-phenylpyridine)(acetylacetonate)iridium [Ir(ppy)2(acac)] EML. A series of reference films and single carrier devices were fabricated and studied to understand the difference between CuI and IrIII complex based nondoped OLEDs.
Co-reporter:Weibo Yan, Yunlong Li, Weihai Sun, Haitao Peng, Senyun Ye, Zhiwei Liu, Zuqiang Bian and Chunhui Huang
RSC Advances 2014 vol. 4(Issue 62) pp:33039-33046
Publication Date(Web):14 Jul 2014
DOI:10.1039/C4RA05578K
Thin polythiophene film prepared via electrochemical polymerization has been successfully used as the hole-transporting layer in CH3NH3PbI3 perovskite solar cells, affording a series of ITO/polythiophene/CH3NH3PbI3/C60/BCP/Ag devices. The highest occupied molecular orbit (HOMO) and lowest unoccupied molecular orbit (LUMO) of the polythiophene film are determined as −5.20 eV and −3.12 eV, respectively, which match well with that of CH3NH3PbI3 perovskite material. In addition, a promising power conversion efficiency of 11.8%, featuring a high fill factor of 0.707, good open voltage of 1.03 V and short current density of 16.2 mA cm−2, has been obtained, which renders polythiophene as an effective competitor to spiro-OMeTAD in perovskite solar cells. Furthermore, this work provides a simple, prompt, controllable and economic approach for the preparation of hole-transporting layer, which would undoubtedly yield new insight into the industrial production of perovskite solar cells.
Co-reporter:Zhiwei Liu, Michael G. Helander, Zhibin Wang, Zhenghong Lu
Organic Electronics 2013 Volume 14(Issue 3) pp:852-857
Publication Date(Web):March 2013
DOI:10.1016/j.orgel.2013.01.009
A series of two component phosphorescent organic light-emitting diodes (PHOLEDs) combing the direct hole injection into dopant strategy with a gradient doping profile were demonstrated. The dopant, host, as well as molybdenum oxide (MoO3)-modified indium tin oxide (ITO) anode were investigated. It is found that the devices ITO/MoO3 (0 or 1 nm)/fac-tris(2-phenylpyridine)iridium [Ir(ppy)3]:1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene (TPBi) (30 → 0 wt%, 105 nm)/LiF (1 nm)/Al (100 nm) show maximum external quantum efficiency (EQE) over 20%, which are comparable to multi-layered PHOLEDs. Moreover, the systematic variation of the host from TPBi to 4,7-diphenyl-1,10-phenanthroline (Bphen), dopant from Ir(ppy)3 to bis(2-phenylpyridine)(acetylacetonate)iridium [Ir(ppy)2(acac)], and anodes between ITO and ITO/MoO3 indicates that balancing the charge as well as controlling the charge recombination zone play critical roles in the design of highly efficient two component PHOLEDs.Graphical abstractHighlights► A high efficiency (EQEmax = 21.9%, PEmax = 86 lm/W and CEmax = 74 cd/A) two component PHOLED was explored. ► Different dopants [Ir(ppy)3 and Ir(ppy)2(acac)], hosts (TPBi and Bphen), and anodes (ITO and ITO/MoO3) were compared. ► Charge balance plays a critical role in the design of highly efficient two component PHOLEDs. ► Improvement of device performance and low-cost mass production are possible.
Co-reporter:Zifeng Zhao, Gang Yu, Qiaowen Chang, Xiaochen Liu, Yang Liu, Liding Wang, Zhiwei Liu, Zuqiang Bian, Weiping Liu and Chunhui Huang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 29) pp:NaN7351-7351
Publication Date(Web):2017/06/29
DOI:10.1039/C7TC01594A
A high triplet energy level (ET) and balanced carrier mobility are critical factors for host materials in efficient blue phosphorescent organic light-emitting diodes (PHOLEDs). Herein, we report a facile synthesis of four compounds, dicarbazolylphenylphosphine (DCPP), dicarbazolylphenylphosphine oxide (DCPPO), tricarbazolylphosphine (TCP), and tricarbazolylphosphine oxide (TCPO), and their application as host materials in a classic blue phosphorescent emitter bis[2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato)iridium(III) (FIrpic). The four compounds show a high ET of up to 3.0 eV and tunable mobilities. We fabricated four OLEDs with a device structure of ITO/MoO3 (1 nm)/N,N′-dicarbazolyl-3,5-benzene (mCP):MoO3 (20 wt%, 10 nm)/mCP (30 nm)/Host:FIrpic (7 wt%, 20 nm)/1,3,5-tri(m-pyrid-3-yl-phenyl) benzene (TmPyPB, 40 nm)/LiF (1 nm)/Al (100 nm), all of which display maximum external quantum efficiencies (EQEs) exceeding 20%. The DCPPO-based device reaches the highest EQE of 27.5%, the maximum luminance of 14070 cd m−2, and the lowest efficiency roll-off of 22.2% from 1 to 10 mA cm−2, which is among the best-performing FIrpic-based PHOLEDs without using any light extraction method.
Co-reporter:Tianchi Ni, Xiaochen Liu, Tao Zhang, Hongliang Bao, Ge Zhan, Nan Jiang, Jianqiang Wang, Zhiwei Liu, Zuqiang Bian, Zhenghong Lu and Chunhui Huang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 22) pp:NaN5843-5843
Publication Date(Web):2015/05/01
DOI:10.1039/C5TC00727E
Inexpensive materials made of abundant natural resources such as CuI complexes are essential to sustain the development of organic light emitting diode (OLED) technology for mass market applications such as solid-state illumination. CuI complexes, however, mostly are neither soluble nor stable toward sublimation, which is a road block for the development of efficient CuI complex based OLEDs using traditional methods of synthesis, sublimation and vacuum evaporation. In this work, two isoquinolyl carbazole (CIQ) compounds 9-(8-(carbazol-9-yl)isoquinolin-5-yl)-carbazole (DCIQ) and 9-(4-(5-(4-(carbazol-9-yl)phenyl)isoquinolin-8-yl)phenyl)-carbazole (DCDPIQ) were synthesized to codeposition with copper iodide (CuI) to form red emissive dimeric CuI complex doped film in situ, which could be utilized directly as the emissive layer (EML) in OLEDs. After a systematic study of the two compounds and their codeposited CuI:CIQ films, as well as optimizing the CuI doping concentration, it is found that red OLEDs can be achieved, showing a maximum emission band, an external quantum efficiency (EQE), a luminance of 643 nm, 3.5%, 3290 cd m−2 for DCIQ, and 635 nm, 3.6%, 853 cd m−2 for DCDPIQ, respectively.
Co-reporter:Feng Wei, Jacky Qiu, Xiaochen Liu, Jianqiang Wang, Huibo Wei, Zhibin Wang, Zhiwei Liu, Zuqiang Bian, Zhenghong Lu, Yongliang Zhao and Chunhui Huang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 31) pp:NaN6341-6341
Publication Date(Web):2014/06/30
DOI:10.1039/C4TC00410H
Inexpensive and eco-friendly luminescent Cu(I) complexes are ideal phosphorescent emitters for high efficiency organic light-emitting diodes (OLEDs). A series of pyrazinyl carbazole (CPz) compounds were designed and synthesized to obtain efficient luminescent Cu(I) complexes through reaction with CuI using a vacuum codeposition method. Based on photophysical studies of the CPz compounds and their codeposited CuI–CPz films, the compound 9-(3-(6-(carbazol-9-yl)pyrazin-2-yl)phenyl)-carbazole (CPzPC) with CuI was chosen as the emissive layer for OLED fabrication, where the emitter was identified as Cu2(μ-I)2(CPzPC)4 on the basis of X-ray absorption spectroscopy. After optimizing the device architecture and material selection including the CuI doping concentration and hole transporting layer, an efficient orange-red emitting OLED with a maximum emission band, an external quantum efficiency (EQE), and a luminance of 590 nm, 6.6% and 8619 cd m−2 (10 V), respectively, was achieved.
Co-reporter:Ziran Zhao, Weihai Sun, Yunlong Li, Senyun Ye, Haixia Rao, Feidan Gu, Zhiwei Liu, Zuqiang Bian and Chunhui Huang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 10) pp:NaN4773-4773
Publication Date(Web):2017/02/10
DOI:10.1039/C6TA10305G
Organo-metal halide perovskite solar cells have shown great potential for application in photovoltaics with their high power conversion efficiency. For the future commercialisation of perovskite solar cells, it is crucial to simplify their device structures while maintaining their efficiency. In this review, we discuss the recent progress in the simplification of device structures for low-cost, high-efficiency perovskite solar cells after briefly reviewing the evolution of the device structures of perovskite solar cells.
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