Jian Wang

Beijing Jiaotong University, Peping, Beijing, China

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Publications (51)121.76 Total impact

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    ABSTRACT: A series of solution processed organic solar cells (OSCs) were fabricated with a two-dimensional conjugated small molecule SMPV1 as electron donor and fullerene derivatives PC71BM or ICBA as electron acceptor. The champion power conversion efficiency (PCE) of OSCs arrives to 7.05% for the cells with PC71BM as electron acceptor. A relatively large open circuit voltage (VOC) of 1.15 V is obtained from cells using ICBA as electron acceptor with an acceptable PCE of 2.54%. The fill factor (FF) of OSCs is 72% or 61% for the cells with PC71BM or ICBA as electron acceptor, which is relatively high value for small molecule OSCs. The relatively low performance of OSCs with ICBA as electron acceptor indicates that ICBA cannot play positive role in photoelectric conversion processes, which is very similar to the phenomenon observed from the OSCs with high efficient narrow band gap polymers other than P3HT as electron donor, the underlying reason is still in debate. The SMPV1 has strong self-assemble ability to form an ordered two dimensional lamellar structure, which provides an effective platform to investigate the effect of electron acceptor chemical structure on the performance of OSCs. Experimental results exhibit that ICBA molecules may prefer to vertical cross-intercalation among side chains of SMPV1, PC71BM molecules may have better miscibility with SMPV1 in the active layer. The different donor/acceptor (D/A) intermolecular arrangement strongly influences photon harvesting, exciton dissociation and charge carrier transport, which may provide a new sight on performance improvement of OSCs by adjusting D/A intermolecular arrangements.
    Organic Electronics 09/2015; 24. DOI:10.1016/j.orgel.2015.05.010 · 3.68 Impact Factor
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    ABSTRACT: We report a trap-assisted photomultiplication (PM) phenomenon in solution-processed polymer photodetectors (PPDs) based on P3HT:PC71BM as the active layer, the maximum EQE of 16,700% is obtained for the PPDs with PC71BM doping weight ratio of 1%. The PM phenomenon is attributed to the enhanced hole tunneling injection assisted by trapped electrons in PC71BM near Al cathode, which can be demonstrated by the transient photocurrent curves and EQE spectra of PPDs with different PC71BM doping ratios. The positive effect of trapped electrons in PC71BM near Al cathode on the hole tunneling injection is further confirmed by the simulated optical field and exciton generation rate distributions in the active layer and the EQE spectra of PPDs with Al(1)/P3HT:PC71BM(100:1)/Al(2) device structure under forward and reverse biases. This discovery may open a new road for organic materials to be used in highly sensitive photodetectors while preserving the advantages of organic materials.
    Scientific Reports 03/2015; 5:9181. DOI:10.1038/srep09181 · 5.08 Impact Factor
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    ABSTRACT: Polymer solar cells (PSCs) with poly(diketopyrrolopyrrole-terthiophene) (PDPP3T): [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as active layers were fabricated from different temperature solutions. The champion power conversion efficiency (PCE) of PSCs prepared from hot solution is about 6.22%, which is better than that of 5.54% for PSCs prepared from cool (room temperature) solution and 5.85% for PSCs prepared from cool solution with 1,8-diiodooctane (DIO) solvent additive. The underlying reasons on PCE improvement of PSCs prepared from hot solution should be attributed to the more dispersive donor and acceptor distribution in the active layer, resulting in the better bi-continuous interpenetrating network for exciton dissociation and charge carrier transport. The enhanced and more balanced charge carrier transport in the active layer is obtained for the PSCs prepared from hot solution, which can be demonstrated from the J-V curves of the related hole-only and electron-only devices.
    Physical Chemistry Chemical Physics 03/2015; DOI:10.1039/C5CP00963D · 4.20 Impact Factor
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    ABSTRACT: A smart strategy is reported to obtain photomultiplication (PM) type polymer photodetectors (PPDs) based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) which are commonly used in polymer solar cells. The PPDs with 1 wt% PC61BM exhibit a champion EQE of 37,500% under 625 nm illumination with an intensity of 8.87 μW cm-2 at -19 V bias. The PM phenomenon of PPDs with rather low PC61BM doping ratios should be attributed to the enhanced hole tunneling injection assisted by trapped electrons in PC61BM near the Al cathode which can be completely demonstrated from i) turning distribution of electron traps by changing P3HT:PC61BM doping weight ratios from 200:1 to 1:1; ii) adjusting interfacial barrier width by inserting LiF layer between the active layer and the Al cathode.
    ACS Applied Materials & Interfaces 02/2015; 7(10). DOI:10.1021/acsami.5b00041 · 5.90 Impact Factor
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    ABSTRACT: We present a smart strategy to simultaneously increase the short circuit current (Jsc), the open circuit voltage (Voc) and the fill factor (FF) of the polymer solar cells (PSCs). A two-dimensional conjugated small molecule material (SMPV1), as the second electron donor, was doped into the blend system of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C71-butyric acid methyl (PC71BM) to form ternary PSCs. The ternary PSCs with 5 wt% SMPV1 doping ratio in donors achieve 4.06% champion power conversion efficiency (PCE), corresponding to about 21.2% enhancement compared with the 3.35% PCE of P3HT:PC71BM-based PSCs. The underlying mechanism on performance improvement of ternary PSCs can be summarized as (i) harvesting more photons in the longer wavelength region to increase Jsc; (ii) obtaining the lower mixed HOMO energy level by incorporating SMPV1 to increase Voc; (iii) forming the better charge carrier transport channel through the cascade energy level structure, optimized morphology and phase separation of donor/acceptor materials to increase Jsc and FF.
    ACS Applied Materials & Interfaces 01/2015; DOI:10.1021/acsami.5b00308 · 5.90 Impact Factor
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    ABSTRACT: Polymer solar cells (PSCs) with different anode buffer layers were fabricated to investigate dipole-assisted hole extraction on the performance improvement of PSCs. The power conversion efficiency (PCE) of PSCs was increased from 4.77% to 6.18% with 29.6% improvement due to the increased short circuit current density (Jsc) from 12.00 to 15.65 mA/cm2 induced by the oriented LiF dipole-assisted hole extraction. More hole could be swept-out from the active layers by oriented LiF dipole/PEDOT:PSS combined anode buffer layers. The dipole-assisted hole extraction could be further demonstrated from the J–V curves of hole-only devices with different anode buffer layers.
    Solar Energy Materials and Solar Cells 11/2014; 130:15–19. DOI:10.1016/j.solmat.2014.06.030 · 5.03 Impact Factor
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    ABSTRACT: A series of high performance of polymer solar cells (PSCs) were fabricated with poly[(4,8-bis-(2-ethylhexyloxy)-benzo[1,2-b:4,5-b′](dithiophene)-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno [3,4-b]thiophene)-2,6-diyl] (PBDTTT-EFT) as the donor and with [6,6]phenyl-C71-butyric acid methyl ester (PC71BM) as the acceptor. The PSCs processed with DCB/CB mixed solvents show an open circuit voltage (Voc) of 0.79 V, a short circuit current density (Jsc) of 13.63 mA/cm2 and a fill factor (FF) of 62.9%, resulting in the highest PCE of 6.77% compared with PCE of 5.99% for CB as solvent and PCE of 5.39% for DCB as solvent. The PCE of PSCs processed with DCB/CB mixed solvents is further increased to 7.58% from 6.77% by chloroform vapor annealing treatment for 60 seconds. The PCE improvement should be attributed to the optimized bi-continuous interpenetrating networks of PBDTTT-EFT:PC71BM for better exciton dissociation and charge carrier collection.
    RSC Advances 09/2014; 4(89). DOI:10.1039/C4RA09417D · 3.71 Impact Factor
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    ABSTRACT: A series of polymer solar cells (PSCs) based on poly (diketopyrrolopyrrole-terthiophene) (PDPP3T) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as active layer were fabricated to investigate the effect of 1,8-diiodooctane (DIO) on the performance of PSCs. The power conversion efficiency (PCE) of PSCs was increased from 3.77 % to 4.37 % for the cells with DIO additive. The underlying reason may be attributed to that DIO additive could make PC71BM more dispersive in the active layer, forming a better bi-continuous interpenetrating network for excition dissociation and charge carrier transport. Therefore, the short circuit current density (J SC) and fill factor (FF) was increased from 8.25 to 9.18 mA/cm2 and from 67.2 % to 70.0 % for the PSCs with DIO additive compared with PSCs without DIO additive.
    Chinese Science Bulletin 09/2014; 59(26). DOI:10.1007/s11434-014-0436-x · 1.37 Impact Factor
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    ABSTRACT: The effect of 1,8-diiodooctane (DIO) on the performance enhancement of polymer solar cells (PSCs) based on [6,6]phenyl-C71-butyric acid methyl ester (PC71BM) as the acceptor and poly[(4,8-bis-(2-ethylhexyloxy)-benzo[1,2-b:4,5-b′](dithiophene)-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno[3,4-b]thiophene)-2,6-diyl](PBDTTT-C) as the donor was investigated from the device physics researches. The short circuit current density (Jsc) was increased from 8.84 to 12.11 mA/cm2, fill factor (FF) was increased from 44.5% to 63.1%, resulting in power conversion efficiency (PCE) with 80% improvement from 2.95% to 5.35% by adding DIO with 3% volume ratio. The enhancement of performance of PSCs could be mainly attributed to the improved charge carrier transport and increased optical field strength in the active layer by adding DIO additive.
    Applied Surface Science 06/2014; 305:221–226. DOI:10.1016/j.apsusc.2014.03.041 · 2.54 Impact Factor
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    ABSTRACT: We present performance improved ternary bulk heterojunction polymer solar cells by doping a small molecule 2,4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl] squaraine (DIB-SQ) into the common binary blend of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). The optimized power conversion efficiency (PCE) of P3HT:PC71BM-based cells was improved from 3.05% to 3.72% by doping 1.2 wt% DIB-SQ as the second electron donor, which corresponds to about 22% PCE enhancement. The main contributions of doping DIB-SQ material on the improved performance of PSCs can be summarized as: i) harvesting more photons in low energy range, ii) increased exciton dissociation, energy transfer and charge carrier transport in the ternary blend films. The energy transfer process from P3HT to DIB-SQ is demonstrated by time-resolved transient photoluminescence spectra through monitoring the lifetime of 700 nm emission from neat P3HT, DIB-SQ and blended P3HT:DIB-SQ solutions. The lifetime of 700 nm emission is increased from 0.9 ns for neat P3HT solution, 4.9 ns for neat DIB-SQ solution to 6.2 ns for P3HT:DIB-SQ blend solution.
    ACS Applied Materials & Interfaces 04/2014; 6(9). DOI:10.1021/am500074s · 5.90 Impact Factor
  • International Journal of Photoenergy 01/2014; 2014:1-6. DOI:10.1155/2014/846581 · 2.66 Impact Factor
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    ABSTRACT: Lighting accounts for approximately 22 percent of the electricity consumed in buildings in the United States, with 40 percent of that amount consumed by inefficient incandescent lamps. This has generated increased interest in the use of white electroluminescent organic light-emitting devices (WOLEDS) as the next generation solid-state lighting source, owing to their potential for significantly improved efficiency over incandescent sources, combined with low-cost, high-throughput manufacturability. The research and application of the devices have witnessed great progress. WOLEDS have incomparable advantages for its special characteristics. This progress report sketched the principle of WOLEDS and provided some common structures, and further investigation of the mechanism of different structures was made. Meanwhile, the key technologies of WOLEDS were summarized. Finally, the latest research progress of WOLEDS was reviewed.
    Guang pu xue yu guang pu fen xi = Guang pu 01/2014; 34(1):27-33. DOI:10.3964/j.issn.1000-0593(2014)01-0027-07 · 0.27 Impact Factor
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    ABSTRACT: Anew type of organic visible-blind ultraviolet (UV) photodetector based on tri(dibenzoylmethane)(4, 7-biphenyl-1,10-phenanthroline)europium () [Eu(DBM)3BPhen] as an electron donor and [6,6]-phenyl-C-61-butyric acid methyl ester ([60]PCBM) as an electron acceptor was fabricated. A peak response of 26 mA·W-1 and external quantum efficiency of 9.1% were obtained under illumination with 360 nm UV light at 2.1 mW·cm-2. This was because of the high UV absorption of Eu(DBM)3BPhen and the long lifetime, 300 μs, of Eu3+ ions, resulting in high exciton dissociation efficiency. Distinct photoluminescence quenching and photoconductivity of Eu(DBM)3BPhen were obtained by doping with [60]PCBM. A strong persistent photoconductivity was observed, which could be attributed to low charge carrier transportation and slow release of trapped exciton states in the blend films after the UV light is turned off.
    ACTA PHYSICO-CHIMICA SINICA 12/2013; 29(12). DOI:10.3866/PKU.WHXB201310301 · 0.89 Impact Factor
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    ABSTRACT: Organic light-emitting diodes (OLEDs) are considered as an ideal in next generation of flat panel displays and solid state lighting source. Still, the stability and efficiency of OLEDs remain great challenges for its commercialization application. This article provides an overview on working principle of different kinds of luminescence, effective methods to improve quantum efficiency, recent progress of white emission OLEDs, novel types of transparency electrode for flexible OLEDs and the stability of OLEDs. A series of interesting and promising ideas to improve the performance of OLEDs are summarized from physical engineering based on the recent achievement of high brightness, high efficient and good stability of OLEDs.
    Journal of Photochemistry and Photobiology C Photochemistry Reviews 12/2013; 17:69–104. DOI:10.1016/j.jphotochemrev.2013.08.001 · 11.63 Impact Factor
  • Solar Energy Materials and Solar Cells 11/2013; 118:135-140. DOI:10.1016/j.solmat.2013.08.013 · 5.03 Impact Factor
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    ABSTRACT: A new type of organic visible-blind UV-PDs is demonstrated by utilizing phosphorescent material Ir(III)bis[(4,6-difluorophenyl)-pyridinato-N, C<sup>2<sup>'</sup> </sup>] picolinate (FIrpic) as the electron donor and [6,6]-phenyl-C-61-butyricacidmethylester (PCBM) as the electron accepter, respectively. The peak responsivity of the organic UV-PDs is as high as 140 mA/W, corresponding to an external quantum efficiency of about 48%, under 365 nm UV light with an intensity of 0.018 mW/cm<sup>2</sup>. The distinct photoluminescence quenching of FIrpic is obtained by doping PCBM. The organic UV-PDs provide visible-blind performance with the strong photocurrent response in the UV-A region, the rise and fall times of less than one second, and linear response within the incident light-intensity range from 0.018 to 20 mW/cm<sup>2</sup>.
    Optics Letters 10/2013; 38(19):3823-3826. DOI:10.1364/OL.38.003823 · 3.18 Impact Factor
  • Yang Liu, Fujun Zhang, Jian Wang
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    ABSTRACT: Organic small material lead phthalocyanine (PbPc) nanocolumns were prepared via glancing angle deposition (GLAD) on indium tin oxide (ITO) coated glass substrates. Organic electron acceptor materials fullerene (C60) was evaporated onto the nanocolumn PbPc thin films to prepare heterojunction structure ITO/PbPc/C60/Bphen/Al organic photovoltaic cells (OPVs). It is worthwhile to mention that C60 molecules firstly fill the voids between PbPc nanocolumns and then form impact C60 layer. The interpenetrating electron donor/acceptor structure effectively enhances interface between electron donor and electron acceptor, which is beneficial to exciton dissociation. The short circuit current density (Jsc) of organic photovoltaic devices (OPVs) based on PbPc nanocolumn was increased from 1.19 mA/cm2 to 1.74 mA/cm2, which should be attributed to the increase of interface between donor and acceptor. The effect of illumination intensity on the performance of OPVs was investigated by controlling the distance between light source and sample, and the Jsc of two kind of OPVs was increased along with the increase of illumination intensity.
    International Journal of Photoenergy 04/2013; 2013. DOI:10.1155/2013/346818 · 2.66 Impact Factor
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    ABSTRACT: Two kinds of emission colour-tunable phosphorescent organic light-emitting diodes (PhOLEDs) were realized by changing the Ir(III) bis [2-(4,6-difluorophenyl)-pyridinato-N,C2'] (picolinate) (FIrpic) doping levels in the host polymer poly(9-vinylcarbazole) (PVK) or by adjusting the driving voltage on the devices with neat FIrpic film as the emission layer. The Commission Internationale del'Eclairage (CIE) coordinates of PhOLEDs could be changed from (0.14, 0.37) to (0.29, 0.55) by adjusting the FIrpic doping levels from 0.08 : 1 to 2 : 1 in the host polymer PVK. It is worthwhile to mention that all PhOLEDs with a FIrpic : PVK film as the emission layer show high emission colour stability dependence on the driving voltage. The photoluminescence emission colour tunability of the FIrpic : PVK films was also observed under the same excitation conditions when the FIrpic : PVK doping level was changed, which is very similar to that observed from electroluminescence (EL) emission of PhOLEDs. For devices with a neat FIrpic film as the emission layer, the EL emission colour of the PhOLEDs could be adjusted by the driving voltage. The CIE coordinates of the PhOLEDs could be tuned from (0.31, 0.50) to (0.44, 0.50) along with an increase in driving voltage from 8 to 20 V. The emission colour tunability of the neat FIrpic or FIrpic : PVK films should be attributed to the FIrpic self-absorption effect and the occurrence of a new emission peak at about 530 nm. The emission peak at about 530 nm was proved to be FIrpic excimer emission by investigating this emission intensity dependence on FIrpic doping levels in PVK or photo/electric-excitation density on FIrpic : PVK and neat FIrpic films.
    Journal of Physics D Applied Physics 11/2012; 46(1):015104. DOI:10.1088/0022-3727/46/1/015104 · 2.52 Impact Factor
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    ABSTRACT: To analyze the differences and correlation between the ganglion cell complex (GCC), peripapillary retinal nerve fiber layer (pRNFL) and mean deviation (MD), mean sensitivity (MS) of saddle area tumor patients, and to evaluate the feasibility of using OCT to diagnose the visual pathway damage of saddle area tumor patients. It was a case-control study. One hundred and eighty-eight normal persons and 279 saddle area tumor patients treated in Beijing Tiantan hospital, from November 2010 to June 2011, were recruited; the saddle area tumor patients were diagnosed by surgical sample pathological analysis. The recruits were divided into four groups, including the normal group, the pituitary gland tumours group, the meningiomas group and the craniopharynglomas group. All patients received the visual field (VF) test using the Octopus 900 automated perimeter with the central 30 degree program, and the mean thickness measurements of GCC and pRNFL were made by RTVue OCT. The Spearman rank correlation coefficient was used to assess the correlation between GCC, pRNFL and MD, MS. The differences between pRNFL and GCC among the four groups were compared. The average thickness of the pRNFL (r(sOD) = 0.369 - 0.735, r(sOS) = 0.369 - 0.691) and GCC (r(sOD) = 0.357 - 0.797, r(sOS) = 0.375 - 0.681) were correlated with MD and MS (P < 0.01), and the measurements from the meningiomas was the most significant. Comparing with the normal group's thickness of pRNFL and GCC [OD: (113.60 ± 9.13) µm and (98.04 ± 6.85) µm; OS: (114.06 ± 8.99) µm and (97.70 ± 5.83) µm], the pituitary gland tumours group [OD: (101.25 ± 19.95) µm and (91.08 ± 13.19) µm; OS: (99.96 ± 20.95) µm and (89.82 ± 15.47) µm], meningiomas group [OD:(89.54 ± 19.19) µm and (80.77 ± 10.43) µm; OS: (92.79 ± 22.00) µm and (80.43 ± 10.09) µm] and craniopharynglomas group [OD: (94.96 ± 16.59) µm and (86.46 ± 11.65) µm; OS: (94.92 ± 15.77) µm and (86.77 ± 9.56) µm] were thinner. There was statistically significant difference of pRNFL and GCC, among the three tumor groups, and the thickness of pRNFL and GCC of the meningiomas group was the thinnest (P < 0.05). The average thickness of the pRNFL and GCC is correlated with vision field damage, which can be used to evaluate optic nerve damage of saddle area tumor patients quantitatively, where the meningiomas was the most significant. The thickness of the pRNFL and GCC was thinner, and the damage to visual functions was more serious. In the three tumor groups, the meningiomas group was the most serious. In the clinic, visual field test combined with OCT were helpful to find and assess the damage to visual pathway and prognosis.
    [Zhonghua yan ke za zhi] Chinese journal of ophthalmology 11/2012; 48(11):1001-4.
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    ABSTRACT: Organic photovoltaic cells (OPVs) have attracted more and more attention due to its highly potential application to solve the energy crisis considering its advantages, such as low cost and ease of large area production. The power conversion efficiency (PCE) of OPVs has undergone a more than nine-fold increase from ∼1.0% by Tang in 1986 to 9.2% in 2010 announced by Mitsubishi Chemical. The major challenges of obtaining high efficiency OPVs are the synthesis of new narrow band gap materials, controlling molecular arrangement, designing novel configuration cells for better photon harvesting in the active layer. In the article, we summarized the recent progress of novel narrow band gap photovoltaic materials and the effective methods to control the morphology of donor and acceptor in the blend films for high performance of OPVs.
    Chinese Science Bulletin 11/2012; 57(32). DOI:10.1007/s11434-012-5202-3 · 1.37 Impact Factor

Publication Stats

243 Citations
121.76 Total Impact Points

Institutions

  • 2010–2015
    • Beijing Jiaotong University
      • • Institute of Optoelectronics Technology
      • • School of Electrical Engineering
      Peping, Beijing, China
  • 2013
    • Shanghai Jiao Tong University
      Shanghai, Shanghai Shi, China
  • 2012
    • Harbin University of Science and Technology
      Charbin, Heilongjiang Sheng, China
  • 2011–2012
    • Beijing Tiantan Hospital
      Peping, Beijing, China
  • 2009–2012
    • Capital Medical University
      • • Department of Neurobiology
      • • Department of Neurosurgery
      Peping, Beijing, China
  • 2007–2009
    • Harbin Engineering University
      • School of Computer Science & Technology
      Charbin, Heilongjiang Sheng, China
    • Harbin University
      Charbin, Heilongjiang Sheng, China