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Ultraviolet ozone (UVO) treatment of molybdenum trioxide (MoO 3 ) appears to be a simple and efficient method for obtaining highly continuous and smooth silver (Ag) thin films in the thermally evaporated MoO 3 /Ag/MoO 3 (MAM) multilayered structure as transparent electrodes for small-molecule organic solar cells (OSCs). It is observed that UVO treatment can oxidatively modify the non-stoichiometric MoO 3 (or MoO 3-x ) surfaces, further increasing the Mo 6+ /Mo 5+ composition ratio and work function of MoO 3-x . Importantly, the use of UVO treatment for the MoO 3 bottom layer effectively improves the wettability of Ag on MoO 3 and enhances the lateral growth of Ag thin film, resulting in a reduction of the percolation threshold thickness of the continuous Ag layer. Due to the formation of an ultrathin Ag interlayer with a continuous and smooth surface morphology, the MAM multilayered electrode after UVO treatment of MoO 3 for 3 min has excellent optical and electrical properties, including a high maximum transmittance of 89.1% and a low sheet resistance of 8.0 Ω/sq. When the optimal UVO-treated MoO 3 /Ag (7.5 nm)/MoO 3 films are used as the anode in OSCs with the copper phthalocyanine (CuPc)/fullerene (C 60 ) planar heterojunction structure, the OSCs have a power conversion efficiency of 0.55%, which is 2.0 and 1.2 times higher than that of devices with untreated MoO 3 /Ag (7.5 nm)/MoO 3 (0.27%) and MoO 3 /Ag (10 nm)/MoO 3 electrodes (0.46%), respectively, and competitive with that of indium-tin-oxide-based devices. Because of almost full surface coverage of the Ag interlayer, UVO treatment of MoO 3 in MAM multilayered electrodes can improve charge carrier injection/extraction at the anode contact and hence improve the photovoltaic performance of OSCs. [ABSTRACT FROM AUTHOR]

Air annealing of MoO 3 bottom layer is a simple and highly efficient surface treatment method to prepare ultrathin, continuous, and smooth Ag layers in MoO 3 /Ag/MoO 3 (MAM) transparent conductive films (TCFs) for indium tin oxide (ITO)-free organic solar cells (OSCs). Air annealing can readily oxidize MoO 3 surface and increase surface energy of the MoO 3 layer, which significantly enhances the adhesion between Ag and MoO 3. When the MoO 3 bottom layer is annealed at 200 °C, moreover, the treatment yields a flatter MoO 3 surface, which positively influences the growth of Ag nanostructures. Eventually, an almost homogeneous, smooth, and continuous surface morphology of the ultrathin Ag films with a thickness of 6.5 nm was obtained. By employing air-annealed MoO 3 bottom layer, the MoO 3 (200 °C, 10 min)/Ag (6.5 nm)/MoO 3 TCF had higher optical transmittance (T av = 83.6%) and lower sheet resistance (R s = 6.5 Ω/sq) than unannealed MAM or commercial ITO TCFs, thereby obtaining the higher value of figure of merit (F TC = 2.6 ×10−2 Ω−1). When used as the transparent electrode in organic solar cells (OSCs), the improved optoelectrical properties of the MoO 3 (200 °C, 10 min)/Ag (6.5 nm)/MoO 3 electrode result in increased short-circuit current density (J sc = 2.27 mA cm−2) and fill factor (FF = 54.8%) of OSCs in comparison to devices based on unannealed MAM and ITO electrodes, leading to an improvement in power conversion efficiency (PCE = 0.62%). From the results of photocurrent measurements, air annealing MoO 3 increases exciton generation in active layers and reduces the carrier back-transfer induced recombination at the anode contact, yielding the enhanced photovoltaic performance. [Display omitted] • Air annealing of MoO 3 can oxidize MoO 3 surface and increase surface energy of the MoO 3 layer. • An almost smooth, and continuous surface morphology of the ultrathin Ag films was obtained by air annealing MoO 3. • Air annealing of the MoO 3 layer increases the figure of merit of MoO 3 /Ag/MoO 3 (MAM) transparent conductive films (TCFs). • Air-annealed MAM-based organic solar cells (OSCs) exhibit the enhanced photovoltaic performance. • Air annealing of MoO 3 in MAM TCFs increases exciton generation and reduces carrier recombination in OSCs. [ABSTRACT FROM AUTHOR]

Abstract: A cathode buffer layer of lithium carbonate (Li2CO3) we used to improve the electro-optical properties of organic light-emitting diodes (OLEDs). Li2CO3 layers with various thicknesses were prepared by thermally evaporating Li2CO3 powders. When a 1-nm-thick Li2CO3 layer was inserted between the aluminum (Al) cathodes and tris(8-hydroxyquinolinato)aluminum (Alq3) electron-transporting layers, device properties such as the turn-on voltage, the maximum luminance, and the device efficiency were improved, becoming better than and comparable to those of devices with LiF and Cs2CO3 buffer layers. The surface of the Alq3 film became smoother after the Li2CO3 layer was deposited. The reaction mechanisms between Li2CO3 and Alq3 were also investigated. X-ray and ultraviolet photoelectron spectroscopy results show that some electrons transfer from Li2CO3 into Alq3, which increases the electron concentration in Alq3 films and moves the Fermi level close to the lowest unoccupied molecular orbital (LUMO) of Alq3. Thus, the electron injection efficiency was enhanced due to a lower electron injection barrier, which improves the charge carrier balance in OLEDs and leads to better device efficiency. [ABSTRACT FROM AUTHOR]

The core density of the defects in perovskite thin films will directly affect the properties of perovskite solar cells. On the other hand, interface engineering is usually being used to effectively improve the quality of perovskite thin films. In this sought of work, MAPbI 3 perovskite thin films were modified by an antisolvent process using trioctylphosphine as a passivator. Trioctylphosphine is a kind of Lewis base and from the experimental results, it is noticed on being contribute to MAPbI 3 grain growth and grain boundary passivation. Due to the grain boundary passivation and grain size increase, the intense defect density inside the grain and at the grain boundary of the MAPbI 3 films is gradually reduced, thereby improving the carrier lifetime, while the hydrophobic property of octyl alkane makes the perovskite thin films less susceptible to air, water and oxygen degraded by the influence. The solar cell which are using the proposed films with the device structure configuration as ITO/SnO 2 /MAPbI 3 /spiro-OMeTAD/Ag and the perovskite layers were modified with trioctylphosphine. Among them, the perovskite thin films showcased to have a best performance when the trioctylphosphine chlorobenzene solution was about 0.15% and the PCE of the device reached for about 12.17%, an increase of 10% was compared with the standard device. In addition, the modified device exhibits good environmental stability, retaining about 90% of the initial efficiency for 100 h in a 70% humidity environment. • The modification of MAPbI 3 perovskite films by trioctylphosphine, which can improve the performance of the solar cell. • The results show that trioctylphosphine as a Lewis base contributes to grain growth and grain boundary passivation. • The hydrophobic properties of octyl alkanes make perovskite films less susceptible to degradation by oxygen and water. • 0.15% of trioctylphosphine chlorobenzene solution is the best ratio. The PCE reaches 12.17%. • After being exposed to a humidity of 70% for 100 h, the device only experiences a 90% decrease in PCE. [ABSTRACT FROM AUTHOR]

In this study, ultraviolet (UV)-ozone treated ultrathin Nb-doped ZnO (NZO) films are developed as an efficient anode buffer layer to improve the overall performance of organic light-emitting diodes (OLEDs). The results show that the UV-ozone treated NZO buffer layer containing 1 mol% of Nb 2 O 5 possesses a higher oxygen content and a greater work function (5.22 eV) as compared to that of an indium tin oxide (ITO) film (~4.7 eV) signifying a reduction in hole injection barrier and thus an improvement in the injection efficiency. In addition, UV-ozone treatment can increase the surface energy of NZO films while reducing their surface roughness. Importantly, the UV-ozone treated 1 nm-thick NZO film with a Nb 2 O 5 doping concentration of 1 mol% can help to lower the turn-on voltage from 3.2 V to 2.8 V, increase the luminance from 10,450 cd/m2 to 25370 cd/m2, and improve the current efficiency from 3.46 cd/A to 5.26 cd/A, (~52 % enhancement as compared to the standard OLED device). Moreover, OLEDs with the developed buffer layer reveal a significant improvement in the roll-off phenomenon under high current densities, indicating a key role of the optimized NZO film in enhancing the carrier balance of the devices. When applied to the p-i-n structure, the NZO film also lead to a superior device performance as compared to the conventional p-i-n structure using NPB:MoO 3 as a hole injection layer, suggesting a widespread use of the developed thin film. These findings therefore show a promising use of the UV-ozone treated NZO ultrathin film as an effective anode buffer material for enhancing OLED overall performance. • Nb 2 O 5 doping, UV-ozone surface treatment, anode buffer layer, organic light-emitting diodes (OLED). [ABSTRACT FROM AUTHOR]

To achieve energy-saving and environmentally friendly warm white lighting through the simplification of white organic light-emitting device (WOLED) structure and manufacturing process, we designed and optimized a WOLED by incorporating bis[2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato)iridium(III)(FIrpic)-doped 4,4′,4′-tris(N-carbazolyl)triphenylamine(TCTA) and bis(4-phenylthieno[3,2- c ]pyridinato-N,C2')(acetylacetonate)iridium(III)(PO-01)-doped 2,2',2′'-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)(TPBI) thin films as the blue and yellow emissive layer (EML), respectively, and forming an exciplex at TCTA and TPBI interface. By adjusting the doping concentration and position within the EML and the thickness of the transport layer, we achieved the optimal emission balance between the blue and yellow colors in the proposed WOLED. We successfully fabricated a highly efficient and structurally simplified WOLED without the use of light extraction coupling techniques, which exhibited high external quantum efficiency (EQE) of 32.6% and current efficiency (CE) of 80.3 cd/A, along with stable emission color with minimal CIE variation of ΔCIE(0.0027, 0.0023) from 500 cd/m² to 5000 cd/m². The experimental results revealed that the designed device structure with the triple host system (TCTA, TPBI, and interface exciplex) facilitated the widening of the recombination zone (RZ), enhanced exciton confinement and utilization, reduced triplet-triplet annihilation (TTA) effects, and achieved efficient host-guest energy transfer. Furthermore, the designed WOLED emitted warm white light spectrum suitable for healthy lighting applications. Therefore, we believe that our work contributes to the further development of ideal and simplified WOLED structure designs for achieving high-efficiency, simplified manufacturing, low-cost, energy-saving, and environmentally friendly healthy lighting. • Highly simplified and efficiency warm WOLED by combining dual EML and interface exciplex systems was successfully fabricated. • High efficiency of 80.2 cd/A with a mild roll-off efficiency of 16.7% is achieved in the reported warm WOLED. • Host-guest energy transfer and efficiency roll-off mechanism is fully discussed. [ABSTRACT FROM AUTHOR]

Abstract: The influence of Mg dopants on the crystalline structures of MZO thin films and the properties of Love wave sensors has been studied in this paper. 0–20mol% Mg doped ZnO films with c-axis preferred orientation were deposited on the 64° YX-LiNbO3 substrates by RF magnetron sputtering technique. XRD, SEM, and AFM measurements investigated characteristics of the films. The phase shift and temperature coefficient of frequency of Love wave devices in MZO/LiNbO3 structures are presented. The appropriate addition of Mg dopant will produce a rough surface to raise the sensitivity. Besides, the effects of reflector gratings on the properties of Love wave sensors are also investigated. [Copyright &y& Elsevier]

Polymer light-emitting diodes (PLEDs) have recently demonstrated the potential for multiple commercial products. However, to realize this potential, several drawbacks of existing designs of PLEDs should be properly addressed, including insufficient luminous efficacy. In this study, a feasible solution to this problem is presented along with the design and fabrication of a novel platinum/nickelous oxide (Pt/NiO x) anode for PLED. The proposed design allows to achieve 40% increase in average current efficiency, four-times increase in the electroluminescence intensity compared to currently available PLEDs, and significantly reduce anode thickness. These results demonstrate that Pt/NiO x can become the mainstream anode material for high-performance PLEDs. [Display omitted] • The NiO x thin film covered with ultrathin Pt layer is used as an anode for PLEDs. • Ultrathin Pt layer makes NiO x surface have uniform conductivity and high WF. • Highly-luminous efficiency and brightness in PLED based on Pt/NiO x anode. • The anode thickness can be greatly reduced for proposed PLED. [ABSTRACT FROM AUTHOR]