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1.
Anal Chem ; 92(5): 3613-3619, 2020 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-32037803

RESUMO

Intracellular lipid metabolism occurs in lipid droplets (LDs), which is critical to the survival of cells. Imaging LDs is an intuitive way to understand their physiology in live cells. However, this is limited by the availability of specific probes that can properly visualize LDs in vivo. Here, an LDs-specific red-emitting probe is proposed to address this need, which is not merely with an ultrahigh signal-to-noise (S/N) ratio and a large Stokes shift (up to 214 nm) but also with superior resistance to photobleaching. The probe has been successfully applied to real-time tracking of intracellular LDs behaviors, including fusion, migration, and lipophagy processes. We deem that the proposed probe here offers a new possibility for deeper understanding of LDs-associated behaviors, elucidation of their roles and mechanisms in cellular metabolism, and determination of the transition between adaptive lipid storage and lipotoxicity as well.

2.
ACS Appl Mater Interfaces ; 12(4): 4659-4672, 2020 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-31898451

RESUMO

In this work, five PTB7-Th-based conjugated polymers (PTB7-Th, PTBSi20, PTBSi25, PTBSi33, and PTBSi100) with different contents of siloxane-terminated pentyl side chain were synthesized, and properties of corresponding blend films with narrow band gap nonfullerene IEICO-4F acceptor were extensively investigated. According to the contact angle testing, the PTB7-Th with 100% alkyl side chain and PTBSi100 100% siloxane-terminated side chain on the benzodithiophene unit showed surface energy values of 40.04 and 34.52 mJ/m2, respectively. The results demonstrate that relative to alkyl side chain in PTB7-Th, the siloxane-terminated side chain could effectively reduce the surface energy of a resulting polymer. Based on Flory-Huggins interaction parameter estimations, the miscibility between the polymer and IEICO-4F would vary in an order of PTB7-Th > PTBSi20 > PTBSi25 > PTBSi33 > PTBSi100, suggesting that siloxane-terminated side chain would afford a tunable driving force for phase separation. Transmission electron microscopy and Raman mapping could confirm large bulk domains inside the PTBSi100:IEICO-4F blend film. In polymer solar cells, the blend film of the PTBSi100 with the lowest miscibility to IEICO-4F showed an undesirable power conversion efficiency (PCE) of 8.52%, which was significantly lower than that of 11.23% for PTB7-Th, suggesting that too large phase separation driving force is not beneficial for the device performance. Side-chain random copolymers PTBSi20, PTBSi25, and PTBSi33 for fine tuning could display PCEs of 11.94, 12.61, and 11.80%, respectively, all higher than that of PTB7-Th. Our results not only reveal the big surface energy difference between the siloxane-terminated side chain and the common alkyl side chain but also provide a guideline for side chain engineering of conjugated polymer donors with tunable morphology and optimal matching with a nonfullerene acceptor.

3.
J Phys Chem Lett ; 10(24): 7905-7909, 2019 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-31786918

RESUMO

Meeting the challenge of direct electrically driven organic semiconductor lasers (OSLs), the design of OSL materials is being studied. Polarized species generally exist in conjugated organic materials and play an important role in the photophysics procedure; therefore, understanding these species is beneficial for designing novel OSL materials. Here, we use the amplified spontaneous emission effect as a medium to reveal a carbazole-benzothiadiazole-based polarized species induced by a charge transfer process. Spectroscopic analysis confirms that this polarized species that acted as a CT pair defect has a negative influence on the ASE stability and solid state fluorescent quantum yield. This inspires us to be cautious in terms of some specific molecular group combinations when designing OSL materials.

4.
Eur J Pharmacol ; 865: 172778, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31705901

RESUMO

The dysregulation of long non-coding RNA (lncRNA) DLX6-AS1 has been identified to be involved in the development of several cancers, but its functional role and the underlying mechanism of DLX6-AS1 in breast cancer (BC) remains unknown. In the current study, the expression of DLX6-AS1 in the BC tissue samples was evaluated and the correlation between DLX6-AS1 expression and clinicopathological parameters were also analyzed. We found that DLX6-AS1 expression was much higher in tumor tissues than that in adjacent normal tissues and was positively associated with poor prognosis in BC patients. DLX6-AS1 knockdown significantly suppressed BC cell proliferation, invasion, migration, and promoted apoptosis. Moreover, luciferase reporter assay validated that DLX6-AS1 acted as an endogenous sponge to miR-505-3p and negatively regulated its expression. Additionally, miR-505-3p inhibited runt-related transcription factor 2 (RUNX2) expression by directly bind to its 3'- untranslated region (3'-UTR) and overexpression of RUNX2 partially reversed the effect of miR-505-3p mimics on BC cell proliferation and invasion. Furthermore, in BC tissues, miR-505-3p expression level was inversely associated with DLX6-AS1 and RUNX2, respectively. In conclusion, these findings demonstrated that DLX6-AS1 functioned as an oncogenic role that promoted BC proliferation and invasion through miR-505-3p/RUNX2 axis, which might serve as a potential therapeutic target for BC treatment.

5.
J Phys Chem Lett ; 10(21): 6878-6884, 2019 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-31612720

RESUMO

Hot exciton luminogens capable of harvesting nonemissive triplet excitons via reverse intersystem crossing from high-order triplet (hRISC) to singlet have great potential in high-efficiency fluorescent organic light-emitting diodes (OLEDs). Although spin-orbit coupling (SOC) is regarded as a key factor affecting the RISC process, its effects on hot exciton materials are poorly understood. Herein, we design and synthesize two blue-emitting hot exciton luminogens, PABP and PAIDO, to study this issue by modulating the excited-state properties. Theoretical and experimental research contributions demonstrate that a stronger SOC between energetically close S1 (π-π*) and Tn (T3, n-π*) of PAIDO gives rise to faster and more efficient hRISC in comparison to that of PABP, leading to a higher external quantum efficiency and a higher exciton utilization efficiency. Crucially, the experimentally measured hRISC rate (khRISC) of hot exciton materials is on the order of 107 s-1, which is much faster than that of the thermally activated delayed fluorescence materials.

6.
Nat Commun ; 10(1): 4100, 2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31506443

RESUMO

Naphthalenediimide-based n-type polymeric semiconductors are extensively used for constructing high-performance all-polymer solar cells (all-PSCs). For such all-polymer systems, charge recombination can be reduced by using thinner active layers, yet suffering insufficient near-infrared light harvesting from the polymeric acceptor. Conversely, increasing the layer thickness overcomes the light harvesting issue, but at the cost of severe charge recombination effects. Here we demonstrate that to manage light propagation within all-PSCs, a thick bulk-heterojunction film of approximately 350 nm is needed to effectively enhance photo-harvesting in the near-infrared region. To overcome the severe charge recombination in such a thick film, a non-halogenic additive is used to induce a well-ordered micro-structure that inherently suppresses recombination loss. The combined strategies of light management and delicate morphology optimization lead to a promising efficiency over 10% for thick-film all-PSCs with active area of 1 cm2, showing great promise for future large-scale production and application of all-PSCs.

7.
ACS Appl Mater Interfaces ; 11(34): 31139-31146, 2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31368304

RESUMO

A novel, efficient, deep-blue fluorescent emitter mPAC, with a meta-connected donor-acceptor structure containing phenanthroimidazole (PPI) as the donor and phenylcarbazole-substituted anthracene (An-CzP) as the acceptor, was designed and synthesized. The meta-linkage provided a highly twisted molecular conformation, which efficiently interrupts the intramolecular π-conjugation, resulting in a deep-blue emission. The optimized nondoped device based on mPAC displayed a deep-blue emission with a narrow full width at half-maximum of 56 nm and Commission Internationale de L'Eclairage coordinates of (0.16, 0.09). The maximum external quantum efficiency (EQEmax) is 6.76%, corresponding to a high exciton utilization efficiency (EUE) of 59.3-88.9%. Experimental results and theoretical analysis indicated that the high EUE is mainly ascribed to the reverse intersystem crossing (RISC) from T2 to S1, a "hot exciton" path in which the large T2-T1 energy gap (1.45 eV) and small T2-S1 energy difference (0.18 eV, T2 > S1) hamper the internal crossing from T2 to T1 and facilitate the RISC process. For the hot exciton path, the T2 state can be feasibly arranged to a high energy level, forming a thermal equilibrium with S1, even slightly higher than the deep-blue S1 to realize an exergonic RISC process, which is usually difficult for the thermally activated delayed fluorescence emitters.

8.
Cancer Chemother Pharmacol ; 84(2): 427-439, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31087138

RESUMO

OBJECTIVE: Although DNA-mismatch-repair-deficient (dMMR) status and aberrant expression of miRNAs are both critically implicated in the pathogenesis of resistance to 5-fluorouracil (5-FU) in colorectal cancer (CRC), whether these two factors regulate tumor response to 5-FU in a coordinated manner remains unknown. This study is designed to elucidate whether changes in miR-552 expression levels correlate to 5-FU-based chemoresistance in CRC, and to further identify the putative targets of miR-552 using multiple approaches. METHODS: miR-552 expression was assessed in 5-FU-resistant CRC tissues and cells using real-time PCR. Effects of miR-552 dysregulation on 5-FU resistance in CRC cells were determined by measuring cell viability, apoptosis and in vivo oncogenic capacity. Finally, we studied the posttranscriptional regulation of SMAD2 by miR-552 using multiple approaches including luciferase reporter assay, site-directed mutagenesis and transient/stable transfection, at molecular and functional levels. RESULTS: Expression of miR-552 was significantly downregulated in 5-FU-resistant CRC tissues and cells, and this downregulation, regulated by dMMR, was associated with poor postchemotherapy prognosis. Functionally, forced expression of miR-552 exhibited a proapoptotic effect and attenuated 5-FU resistance, whereas inhibition of miR-552 expression potentiated 5-FU resistance in CRC cells. Mechanically, miR-552 directly targeted the 3'-UTR of SMAD2, and stable ablation of SMAD2 neutralized the promoting effects of miR-552 deficiency-induced 5-FU resistance. CONCLUSIONS: Overall, our findings have revealed a critical role of miR-552/SMAD2 cascade in modulating cellular response to 5-FU chemotherapy. miR-552 may act as an efficient mechanistic link synchronizing dMMR and 5-FU resistance in CRC.

9.
Front Chem ; 7: 276, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31058144

RESUMO

As one of the three primary colors that are indispensable in full-color displays, the development of red emitters is far behind the blue and green ones. Here, three novel orange-yellow to near-infrared (NIR) emitters based on 5,6-difluorobenzo[c][1,2,5]thiadiazole (BTDF) namely BTDF-TPA, BTDF-TTPA, and BTDF-TtTPA were designed and synthesized. Density functional theory analysis and photophysical characterization reveal that these three materials possess hybridized local and charge-transfer (HLCT) state feature and a feasible reverse intersystem crossing (RISC) from the high-lying triplet state to the singlet state may conduce to an exciton utilization exceeding the limit of 25% of traditional fluorescence materials under electrical excitation. The insertion of thiophene with small steric hindrance as π-bridge between the electron-donating (D) moiety triphenylamine (TPA) and the electron-accepting (A) moiety BTDF not only results in a remarkable 67 nm red-shift of the emission peak but also brings about a large overlap of frontier molecular orbitals to guarantee high radiative transition rate that is of great significance to obtain high photoluminescence quantum yield (PLQY) in the "energy-gap law" dominated long-wavelength emission region. Consequently, an attractive high maximum external quantum efficiency (EQE) of 5.75% was achieved for the doped devices based on these thiophene π-bridged emitters, giving a deep-red emission with small efficiency roll-off. Remarkably, NIR emission could be obtained for the non-doped devices, achieving an excellent maximum EQE of 1.44% and Commission Internationale de l'Éclairage (CIE) coordinates of (0.71, 0.29). These results are among the highest efficiencies in the reported deep-red to NIR fluorescent OLEDs and offer a new π-bridge design strategy in D-π-A and D-π-A-π-D red emitter design.

10.
Adv Mater ; 31(12): e1807388, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30714207

RESUMO

Purely organic electroluminescent materials, such as thermally activated delayed fluorescent (TADF) and triplet-triplet annihilation (TTA) materials, basically harness triplet excitons from the lowest triplet excited state (T1 ) to realize high efficiency. Here, a fluorescent material that can convert triplet excitons into singlet excitons from the high-lying excited state (T2 ), referred to here as a "hot exciton" path, is reported. The energy levels of this compound are determined from the sensitization and nanosecond transient absorption spectroscopy measurements, i.e., small splitting energy between S1 and T2 and rather large T2 -T1 energy gap, which are expected to impede the internal conversion (IC) from T2 to T1 and facilitate the reverse intersystem crossing from the high-lying triplet state (hRISC). Through sensitizing the T2 state with ketones, the existence of the hRISC process with an ns-scale delayed lifetime is confirmed. Benefiting from this fast triplet-singlet conversion, the nondoped device based on this "hot exciton" material reaches a maximum external quantum efficiency exceeding 10%, with a small efficiency roll-off and CIE coordinates of (0.15, 0.13). These results reveal that the "hot exciton" path is a promising way to exploit high efficient, stable fluorescent emitters, especially for the pure-blue and deep-blue fluorescent organic light-emitting devices.

11.
Chem Sci ; 10(4): 1023-1028, 2019 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-30774897

RESUMO

Covalent organic frameworks (COFs) have emerged as a tailor-made platform for designing next-generation two-dimensional materials. However, COFs are produced as insoluble and unprocessable solids, which precludes the preparation of thin films for optoelectronic applications. Here, we report designed synthesis of a highly soluble yet crystalline COF material through the regulation of its inter-layer interactions. The resulting COF is remarkably soluble in a variety of organic solvents and forms stable true solutions with retention of its layered structure. These unique features endow the COF with solution processability; high-quality, large-area COF films can be produced on various substrates in a high-throughput and efficient manner, with good control over the film thickness, making this material compatible with a variety of device applications. The films are electrically anisotropic; the intra-layer carrier conduction is inhibited, while the inter-layer carrier migration is outstanding, showing the highest conductivity among all reported COF materials. Our highly soluble and processable COF may open new pathways for realising high-performance COF-based optoelectronic devices with diverse functions.

12.
Nanoscale ; 11(1): 185-192, 2018 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-30525149

RESUMO

Two-photon excitation (2PE) photodynamic therapy (PDT) is a non-invasive technique for the treatment of cancer. However, its clinical applications are limited by small two-photon absorption cross section values of conventional photosensitizers. Here we designed multifunctional conjugated polymer based nanoparticles consisting of a conjugated polymer, a photosensitizer and a red-emitting dye, which can realize simultaneous 2PE red emission imaging and 2PE-PDT activities. The working principle is based on a 2PE fluorescence resonance energy transfer strategy from the conjugated polymer to photosensitizing and imaging agents. In these nanoparticles (NPs), the conjugated polymer, PPBF, was chosen as a two-photon light-harvesting material while the photosensitizer (tetraphenylporphyrin, TPP) and the red-emitting dye (TPD) were chosen as energy acceptors. The 2PE emission of TPP and TPD was enhanced by up to ∼161 and ∼23 times, respectively. The 2PE-PDT activity of these NPs was significantly improved compared with those NPs without PPBF by up to ∼149 times. Further surface-functionalization with folic acid (FA) groups allows these nanoparticles to exhibit selective affinity toward KB cancer cells. These NPs could act as novel 2PE conjugated polymer based nanoparticles combined with the advantages of low dark cytotoxicity, selective targeting and imaging-guided 2PE-PDT activities.


Assuntos
Nanopartículas/química , Neoplasias/terapia , Fotoquimioterapia , Fármacos Fotossensibilizantes/química , Polímeros/química , Animais , Linhagem Celular Tumoral , Sobrevivência Celular , Corantes/química , Transferência Ressonante de Energia de Fluorescência , Humanos , Lisossomos/química , Camundongos , Microscopia Eletrônica de Transmissão , Microscopia de Fluorescência , Células NIH 3T3 , Fótons , Porfirinas/química , Espécies Reativas de Oxigênio/metabolismo , Oxigênio Singlete/química
13.
ACS Appl Mater Interfaces ; 10(49): 42564-42572, 2018 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-30403343

RESUMO

In the past few years, substantial progress has been made in perovskite light-emitting devices. Both pure green and infrared thin-film perovskite light-emitting devices with external quantum efficiency over 20% have been successfully achieved. However, pure-red and blue thin-film perovskite light-emitting diodes still suffer from inferior efficiency. Therefore, the development of efficient and stable thin-film perovskite light-emitting diodes with pure-red and blue emissions is urgently needed for possible applications as a new display technology and solid-state lighting. Here, we demonstrate an efficient light-emitting diode with pure-red emission based on polymer-assisted in situ growth of high-quality all-inorganic CsPbBr0.6I2.4 perovskite nanocrystal films with homogenous distribution of nanocrystals with size 20-30 nm. With this method, we can dramatically reduce the formation temperature of CsPbBr0.6I2.4 and stabilize its perovskite phase. Eventually, we successfully demonstrate a pure-red-emission perovskite light-emitting diode with a high external quantum efficiency of 6.55% and luminance of 338 cd/m2. Furthermore, the device obtains an ultralow turn-on voltage of 1.5 V and a half-lifetime of over 0.5 h at a high initial luminance of 300 cd/m2.

14.
ACS Appl Mater Interfaces ; 10(46): 39992-40000, 2018 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-30346123

RESUMO

The differences between the introduction of chlorine and fluorine atoms to small-molecule acceptors were deeply investigated. From the single-crystal structures of three molecules, the Cl-substitution intervention into the molecular configuration and packing mainly lies in three aspects as follows: single molecule configuration, one direction of the intermolecular arrangement, and three-dimensional (3D) molecular packing. First, the introduction of the chlorine atom in IDIC-4Cl leads to a more planar molecular configuration than IDIC-4H and IDIC-4F because of the formation of a molecular interlocked network induced by the strong Cl···S intermolecular interactions. Second, IDIC-4Cl shows the closest π-π stacking distance and the smallest dihedral angle (0°) between adjacent molecules to form ideal J-aggregation, which should be beneficial for charge transportation between different connected molecules in this direction. Finally, the interlocked interactions between Cl and S atoms lead to a highly ordered 3D molecular packing, in which the end groups will form an ideal overlapped packing among different molecules, whereas the other two analogues with H or F show less ordered packing of their 1,1-dicyanomethylene-3-indanone ending groups. Organic solar cells based on IDIC-4Cl show the highest power conversion efficiency (PCE) of 9.24%, whereas the PCEs of IDIC-4H- and IDIC-4F-based devices are 4.57 and 7.10%, respectively.

15.
ACS Appl Mater Interfaces ; 10(21): 17519-17525, 2018 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-29770685

RESUMO

The thin-film transistor (TFT) driving circuit is a separate electronic component embedded within the panel itself to switch the current for each pixel in active-matrix organic light-emitting diode displays. We reported a TFT-directed dye electroplating method to fabricate pixels; this would be a new method to deposit films on prepatterned electrode for organic full-color display, where TFT driving circuit provide a switching current signal to drive and direct dye depositing on selected RGB pixels. A prototype patterned color pixel matrix was achieved, as high-quality light-emitting films with uniform morphology, pure RGB chromaticity, and stable output.

16.
Spectrochim Acta A Mol Biomol Spectrosc ; 201: 258-266, 2018 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-29758512

RESUMO

Ion-doped states are significant for improving the performance in organic semiconductor-based devices, which require clear characterization to understand their relationship with conductivity and charge transporting mechanisms. In this paper, Raman spectroscopy is used to track the evolution of a dianion-anion-neutral mixture in a perylene bisimide (PBI)-doped film under air, with z-scanning carried out in the confocal mode. The precise distribution for the different states along the film depth is realized within 3.5 µm. The whole film is clearly divided into three regions: the ion-poor state, transition region and ion-rich state. The ion ratio and distribution are strongly related to the film conductivity and the onset voltage shift. Changes in the distribution of the ionic species during oxidation and electrode catalysis are clearly recorded by z-scanning, which is beneficial for understanding the charge transfer properties as well as the mechanism underlying working devices.

17.
ACS Appl Mater Interfaces ; 10(13): 11377-11381, 2018 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-29536728

RESUMO

The cathode interlayer is of crucial importance for efficient electron injection in inverted polymer light-emitting diodes (PLEDs) to realize high electroluminescence efficiency. Here, a novel photoconductive cathode interlayer based on organic dye-doped ZnO (ZnO:PBI-H) is applied as the cathode buffer layer in PLEDs, and dramatically enhanced device performance is obtained. The photodoping of ZnO may greatly promote the electron injection ability under the device working conditions, which increases the electron-hole recombination efficiency when using P-PPV as the light-emitting material. Thanks to the decreased energy barrier between the cathode interlayer and the light-emitting layer, the turn-on voltage of the PLEDs is obviously reduced when using the photoconductive cathode interlayer. Our results indicate that photodoping of the cathode interlayer is a promising strategy to increase the interlayer performance in light-emitting diodes.

18.
ACS Appl Mater Interfaces ; 10(12): 10270-10279, 2018 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-29512383

RESUMO

Poly[(9,9-dioctyl-2,7-fluorene)- alt-(9,9-bis(3'-( N, N-dimethylamino)propyl)-2,7-fluorene)] (PFN) is a very important interfacial modifier in organic photovoltaic and organic light-emitting diodes to improve device performance, where their molecular dipole has been regarded to play a key role. In this work, we have reported a spontaneous interfacial dipole orientation effect in acetic acid dissolved PFN, which is strongly related to the interfacial dipole and the corresponding device performance. In direct spin-coating, the interfacial dipole is 1.08 Debye with interfacial contact angle 84.8°, whereas after self-assembly of 10 min, the interfacial dipole is balanced at 4.21 Debye, with the interfacial contact angle decreasing to 76.8°. Without strong interaction with the substrate, the energy of upward amine groups is much lower than that of downward ones in theoretical simulation, which would be the driving force of this spontaneous process. The preferred conformations of PFN molecules on hydroxylated substrates have over 99% amine groups outward, and the theoretical average dipole calculated from the weight of these conformations is 4.48 Debye, which is close to the experimental result and indicates a high ratio of upward amine groups in self-assembled films. This effect obviously changes the device performance, such as an obvious positive threshold voltage shift in transistors and a distinct increase of the short-circuit current/open-circuit voltage in organic solar cells. This effect provides a deeper understanding of the PFN interlayer mechanism and has potential application in optoelectronic devices.

19.
ACS Appl Mater Interfaces ; 10(17): 14956-14965, 2018 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-29517904

RESUMO

A new way to approaching highly emissive BODIPY dyes in both solution and solid state is achieved by introducing intramolecular charge transfer (ICT). A hybrid excited state that shows behaviors of both the ICT excited state and local excited state is discovered to be beneficial in avoiding the disturbance from the rotation vibration of the flexible phenyl substituents. Thus, the nonradiative transition process is suppressed, and the fluorescence efficiency goes up. By modification of the excited state, we realize emission enhancement of crystalline BODIPY derivatives with a PLQY from 0.08 to 0.27, and the compound expresses a good potential application prospect in organic semiconductors.

20.
ACS Appl Mater Interfaces ; 10(12): 10513-10519, 2018 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-29498274

RESUMO

Suitable work function (WF) of the cathode in polymer solar cells (PSCs) is of essential importance for the efficient electron extraction and collection to boost the power conversion efficiency. Herein, we report a facile and efficient method to tune the surface WF of aluminum-doped zinc oxide (AZO) through building of a definite interfacial dipole, which is realized by the construction of a layered structure of positive and negative ionized species. A cross-linked perylene bisimide (poly-PBI) thin film is deposited onto the AZO surface first, and then it is reduced to the radical anion state (poly-PBI•-) in an electrochemical cell, using tetraoctylammonium (TOA+), a bulky cation, as a counter ion. Owing to the huge volume of TOA+, it is absorbed on the surface of the cross-linked PBI•- thin film through Coulomb force, and thus a definite interface dipole is formed between the two ionized layers. Because of the definite interface dipole, the surface WF of the electrode modified with ionized layers is decreased dramatically to 3.9 eV, which is much lower than that of the electrode modified with the neutral PBI layer (4.5 eV). By using this novel cathode interlayer with a definite interface dipole in PSCs, a significantly increased open-circuit voltage ( VOC) is obtained. The results indicate that it is a facile and unique method by the construction of a definite interface dipole to tune the surface WF of the electrode for the application in organic electronic devices.

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