Search

A smelting multiple recrystallization strategy and its effects on the morphology, composition, and defects of CsPbBrI2 film were investigated. An optimal number (n = 2) of recrystallization cycles improved the crystallinity and phase purity, minimized the grain boundaries, and optimized the crystal structure, yielding a high-quality perovskite film with significantly reduced defects density. The corresponding photovoltaic devices exhibited a champion efficiency of 16.02% under AM 1.5 G illumination and presented an even higher indoor efficiency of 33.50% under an LED (2956 K, Pin: 334.41 μW/cm2). This recrystallization method offers a promising strategy for developing high-performance indoor and outdoor photovoltaics. Direct recrystallization in the cells was also explored to achieve enhanced stability and longer lifetime in humid conditions.

Over the years, the efficiency of inorganic perovskite solar cells (PSCs) has increased at an unprecedented pace. However, energy loss in the device has limited a further increase in efficiency and commercialization. In this work, we used (NH4)2C2O4·H2O to treat CsPbBrI2 perovskite film during spin-coating. The CsPbBrI2 underwent secondary crystallization to form high quality films with micrometer-scale and low trap density. (NH4)2C2O4·H2O treatment promoted charge transfer capacity and reduced the ideal factor. It also dropped the energy loss from 0.80 to 0.64 eV. The resulting device delivered a power conversion efficiency (PCE) of 16.55% with an open-circuit voltage (Voc) of 1.24 V, which are largely improved compared with the reference device which exhibited a PCE of 13.27% and a Voc of 1.10 V. In addition, the optimized treated device presented a record indoor PCE of 28.48% under a fluorescent lamp of 1000 lux, better than that of the reference device (19.05%).

The market's increasing demand for portable electronic products has made the research in flexible devices very attractive. Flexible solar cells are one of the most eye-catching devices in the field of flexible photovoltaic devices. And the perovskite material has become a powerful candidate material for manufacturing flexible solar cells due to its excellent optical properties, low price and the ability to tolerate more stress accumulation. However, as an active layer, the perovskite film still faces the issue that cracks are easily generated when bending and encountering temperature changes for the limited flexibility. There are many factors that affect the mechanical stability of the perovskite layer: the characteristics of the material itself, the influence of the other layers in the device and the presence or absence of a protective layer. This work reviews some reported strategies of improving the perovskite bending durability, classifies them according to the influencing factors mentioned above, and describes them in detail respectively.

Compared with the rapid development of red and green perovskite light-emitting diodes (PeLEDs), the improvement of the device performance is urgent for blue PeLEDs. Herein, we developed a creative method to incorporate Cl- into quasi-2D perovskite films via dynamic processing, by mixing two main strategies of mixed-Cl/Br perovskites and quasi-2D perovskites. With methylammonium chloride (MACl) treating the perovskite film, the devices presented excellent spectral stability owing to the effective suppression of non-radiative recombination. Consequently, CsPbBr3 : PEABr-based PeLEDs exhibited a maximum external quantum efficiency of 1.74% with a bright luminance of 537 cd m−2. The redshift of the emitting luminescence (EL) peak was no more than 2 nm around 477 nm. The findings in this work will help develop other new routes for pure blue PeLEDs with ideal spectral stability.

A light-emitting organic solar cell (LE-OSC) with electroluminescence (EL) and photovoltaic (PV) properties is successfully fabricated by connecting the EL and PV units using a MoO(3):Al co-evaporation interfacial layer, which has suitable work function and good transmittance. PV and EL units are fabricated based on poly(3-hexylthiophene) (P3HT)-indene-C(60) bisadduct (IC(60)BA) blends, and 4,4′-bis (N-carbazolyl) biphenyl-factris (2-phenylpyridine) iridium (Ir(ppy)(3)), respectively. The work function and the transmittance of the MoO(3):Al co-evaporation are measured and adjusted by the ultraviolet photoelectron spectroscopy and the optical spectrophotometer to obtain the better bi-functional device performance. The forward- and reverse-biased current density-voltage characteristics in dark and under illumination are evaluated to better understand the operational mechanism of the LE-OSCs. A maximum luminance of 1550 cd/m(2) under forward bias and a power conversion efficiency of 0.24% under illumination (100 mW/cm(2)) are achieved in optimized LE-OSCs. The proposed device structure is expected to provide valuable information in the film conditions for understanding the polymer blends internal conditions and meliorating the film qualities. [Image: see text]

Serious issues such as easy-oxidation of Sn2+, fast crystallization rate and high defect density are still existing in tin perovskites to restrain their photovoltaic performance. Herein, a strategy of bottom passivation by potassium thiocyanate (KSCN) has been developed in FA0.75MA0.25SnBrI2-based perovskite solar cells. KSCN interlayer exhibited multifunctional roles in aligning energy levels, assisting perovskite crystallization and promoting charge transport. The resulting champion device delivered superior power conversion efficiency (PCE) as high as 11.17% under AM 1.5G illumination. It is worth noting that the champion indoor photovoltaics efficiency under 2956 K@1062 lux (334.41 μW/cm2) illumination could approach 17.57%, which is the highest PCE for tin perovskite photovoltaics to our knowledge. The outstanding indoor performance demonstrates the huge application potential of eco-friendly tin perovskites.

// Yanhui Lou 1 , Huanhuan Jiang 1 , Zhumei Cui 1 , Lingzhi Wang 1 , Xiangyu Wang 1 and Tian Tian 1 1 Department of Gynecology, Affiliated Hospital of Qingdao University, Qingdao 266100, China Correspondence to: Yanhui Lou, email: lyh7497@163.com Keywords: ovarian cancer, long non-coding RNA, epithelial-to-mesenchymal transition, invasion, metastasis Received: January 16, 2017 Accepted: June 29, 2017 Published: July 25, 2017 ABSTRACT Long intergenic non-protein coding RNA, regulator of reprogramming (linc-ROR) is an intergenic long non-coding RNA (lncRNA) previously shown to contribute to tumorigenesis in several malignancies. However, little is known about whether linc-ROR has a role in ovarian cancer progression. In this study, we found that linc-ROR expression was increased in high-grade ovarian serous cancer tissues compared with normal ovarian tissues or normal fallopian tube tissues. Furthermore, the level of linc-ROR expression was associated with ovarian cancer International Federation of Gynecology and Obstetrics stage and lymph node metastasis. Linc-ROR promoted ovarian cancer cell proliferation both in vitro and in vivo , and contributed to cell migration and invasion. Linc-ROR knockdown in ovarian cancer cell lines inhibited the epithelial-to-mesenchymal transition (EMT) program, which led to ovarian cancer cell metastasis through the repression of canonical Wnt/β-catenin signaling. Together, our results indicated that linc-ROR induces EMT in ovarian cancer cells and may be an important molecule in the invasion and metastasis of ovarian cancer.

Semiconductor nanomaterials with controlled morphologies and architectures are of critical importance for high-performance optoelectronic devices. However, the fabrication of such nanomaterials on polymer-based flexible electrodes is particularly challenging due to degradation of the flexible electrodes at a high temperature. Here we report the fabrication of nickel oxide nanopillar arrays (NiO x NaPAs) on a flexible electrode by vapor deposition, which enables highly efficient perovskite solar cells (PSCs). The NiO x NaPAs exhibit an enhanced light transmittance for light harvesting, prohibit exciton recombination, promote irradiation-generated hole transport and collection, and facilitate the formation of large perovskite grains. These advantageous features result in a high efficiency of 20% and 17% for the rigid and flexible PSCs, respectively. Additionally, the NaPAs show no cracking after 500 times of bending, consistent with the mechanic simulation results. This robust fabrication opens a new opportunity for the fabrication of a large area of high-performance flexible optoelectronic devices.

Solar energy is considered as one of the most promising green energy due to clean, safe, long life, and renewable advantages. Solar cell is an electrical device that converts solar energy directly into electric power on the basis of photovoltaic effect. Fritts built the first solar cell in 1883. Although the initial efficiency was only 1%, it has been exciting to know that the power conversion efficiency of solar cells is endlessly improved since it was reported. Up to now, the efficiency of commercial silicon solar cell is between 10%–18%. The latest research shows that the best efficiency of perovskite solar cell has been improved to be over 20% within several years. As it is well known, the maximum power conversion efficiency of single-junction solar cells are only around 33% according to the Shockley- Queisser limit. With the development of new materials and high technologies, one issue is emerging: What is the ultimate efficiency of solar cells? The highest efficiency of solar cell is possible to break the Schockley-Queisser limit? How to further enhance the efficiency of solar cell? All the questions are hard to answer at present. Surrounding these concerns, this article presents a brief review about the efficiency limits of different solar cells. It might help to understand the ultimate efficiency of solar cells. The details address the basic principle, advantages and disadvantages of single-junction, multi-junction and other new concept solar cells regarding the power conversion efficiency. The review also includes the solar cell materials involving silicon, compound, perovskite, quantum dot, hybrid materials, etc. Finally, we look ahead into the prospect of new concept solar cells and the maximum power conversion efficiency.

Organic-inorganic metal halide perovskites have drawn the interest of scientific community due to their suitable optoelectronic properties and high solar cell efficiency. In this report, we demonstrated, for the first time, the application of Cs2CO3 - doped TiO2 as an efficient electron-transporting layer (ETL) in PSCs. Remarkably, the optimized Cs2CO3-doped TiO2 films exhibited improved wetting properties which assisted the deposition of perovskite films and improved the TiO2/perovskite interface by lowering the work function. With X-ray diffraction studies, better crystalline of the perovskite films could be found in the doped devices. Solar cells prepared with the Cs2CO3-doped TiO2 as ETL resulted in a 19% efficiency performance and improved stability.

Interface engineering is an efficient method for improving the performance of planar perovskite solar cells (PSCs). In this paper, the performance of PSCs was improved significantly by introducing 4,7-diphenyl-1,10-phenanthroline (Bphen) doped with bis(2-methyldibenzo-[f,h]quinoxaline) (Ir(MDQ)2(acac)) to modify the interface between perovskite (CH3NH3PbI3−xClx)/PCBM (phenyl-C61-butyric acid methyl ester) and an Ag electrode. The power conversion efficiency (PCE) was enhanced up to 15.87%, compared with 10.77% for the reference device without interlayer modification. It was found that the enhanced PCE was attributed to the better interface contact between the perovskite and Ag cathode. A suitable interface roughness is beneficial for reducing the leakage current and the probability of carrier recombination, resulting in an enhanced fill factor and thus improved device efficiency.

Monodisperse CdS quantum dots (QDs) are synthesized by thermal decomposition of organic complexes in the system of the cost-effective commercial 0# diesel at 200 °C. The prepared CdS QDs have a good dispersion and high crystallization. When the CdS QDs are doped into the blends of poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6, 6)C61 (PCBM) for hybrid solar cells (HSCs), the HSCs achieve about 25% increase of power conversion efficiency in comparison to the reference device without the CdS QDs. The improvement of the cell performance mainly attributes to the increased short-circuit current density arising from the absorption enhancement in the wavelength range of 350–550 nm by introducing the synthesized CdS QDs into the P3HT: PCBM active layer.

New fabrication techniques for solution-processed organic photovoltaics are more and more desirable due to greater demand for affordable method to make large area. Different from traditional spin-coating, here, we report a new fabrication technique inspired by “liquid-chalk”. Solution can be added into liquid-chalk, and is almost all coated on the devices, while spin-coating will waste most of solution. In addition, large area could be easily achieved with it. Meanwhile, the thickness and roughness could be adjusted by optimizing speed, time of annealing and amount of the solution added. We demonstrated solar cells based on liquid-chalk-coated perovskite photoactive layer (CH3NH3PbI3) exhibit comparatively high power con-version efficiency (PCE) of 14.83% on average. A champion PCE of 16.04% was attained. Similarly, applying the method in pure inorganic system (CsPbBrI2), we also successfully fabricated devices with a highest PCE of 9.17%. The results indicate that using liquid-chalk to coat is an effective new way to fabricate perovskite solar cells, and also an ideal method to make large-area and flexible devices.

A direct comparison of charge transport and electronic traps in representative polymer–fullerene blend, poly (3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 (PCBM), is carried out in dark and illuminated conditions based on the measurements of temperature-dependent current–voltage characteristics. In dark condition, the charge transport presents a transition from Ohmic to trap-limited current. While the trap-filled space charge limited current is observed under illumination at the same applied bias. From evaluations of trap density and energy distribution by a differential method, it is reveal that the diverse charge transport in dark and illuminated conditions is mainly caused by the different trap states distribution, which strongly affects the space charges and the electrical field in P3HT: PCBM blends.

The underlayer plays an important role for organic–inorganic hybrid perovskite formation and charge transport in perovskite solar cells (PSCs). Here, we employ a classical organic small molecule, 5,6,11,12-tetraphenyltetracene (rubrene), as the underlayer of perovskite films to achieve 15.83% of power conversion efficiency with remarkable moisture tolerance exposed to the atmosphere. Experiments demonstrate rubrene hydrophobic underlayer not only drives the crystalline grain growth of high quality perovskite, but also contributes to the moisture tolerance of PSCs. Moreover, the matching energy level of the desirable underlayer is conductive to extracting holes and blocking electrons at anode in PSCs. This introduction of organic small molecule into PSCs provides alternative materials for interface optimization, as well as platform for flexible and wearable solar cells.

Roll-off phenomena in power efficiency for rubrene-based mixed single layer organic light emitting devices is investigated. The evaluation of operational temperature demonstrates that Joule heating is not the main reason for roll-off in power efficiency with current density. Co-doping method through rubrene co-doping with some additive dopant, C6, DCJTB and Nile red, in mixed single layer are proposed for suppressing the roll-off in power efficiency. By co-doping suitable Nile red with rubrene, the efficiency roll-off is found to be largely improved in whole range of current density. Moreover, improved device performance is also realized even if with a 3 wt% fluorescent doping concentration. The improved performance is ascribed that there exists a competitive emission mechanism with respect to different dopant.

Electroluminescence and photovoltaic properties were observed simultaneously in a small molecular rubrene-doped poly(3-hexylthiophene):1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 blends based organic solar cells (OSCs). With optimized rubrene doping ratio, the device showed photovoltaic (PV) property with a power convention efficiency 1.05% under illumination and electroluminescence (EL) characteristics with a maximum luminance 65 cd/m 2 at higher bias, respectively. It provides a new route to realize the PV and EL bi-functional organic devices. In addition, the EL imaging in OSCs is expected to provide valuable information in the film defect conditions for understanding the blends internal conditions, meliorating the film quality, and further improving the device performance.

It will be interesting and valuable information can be achieved if a direct comparison between organic light emitting devices (OLEDs) fabricated by vacuum evaporated method (vac) and solution-based manufacturing processes (sol) was realized. Small molecular OLEDs with a mixed organic layer structure (MOLOLEDs) make it possible for direct comparison between devices with the same materials but fabricated by the two processing methods. This article shows a direct comparison of the luminescence characteristics, charge conduction, and device physics between MOLOLEDs fabricated by vac- and sol-processing techniques. It gives an elementary explain how the organic/metal interfaces influence the charge conduction and device performance.

Injection properties of electrons and holes at the interface of electrodes/active layer for blending poly(3-hexylthiophene) (P3HT) and methanofullerene [6,6]-phenyl–C61–butyric acid methyl ester (PCBM) based on structures of Au/MoO3/P3HT: PCBM/ MoO3/Au as hole dominated device and Al alloy/P3HT: PCBM/Al alloy as electron dominated device were investigated. Both of hole and electron injections were ascribed to Schottky thermionic emission mechanism. The barrier height of carrier injection was estimated under a simulated air mass (AM) 1.5G spectrum illumination and dark conditions, respectively. The interfacial state at Al alloys/ P3HT: PCBM interface was estimated to be 1.4 × 1014 states/cm2/eV under illumination by extrapolating the relation of electron barrier heights and work functions using different Al alloys.

We investigated the carrier injection properties in small molecular organic light emitting devices with a mixed single layer by measuring current–voltage characteristics using Au/MoO 3 as hole and Al alloy as electron injection electrodes. The carrier injection mechanism at the interface was primarily ascribed to the Schottky thermionic emission with the barrier height of 0.25 eV for holes and 0.67 eV for electrons. It was found that the barrier height of the electron was dependent on LUMO level of electron transport material. In addition, the interfacial state analysis demonstrated that the electron barrier height was also dependent on the interfacial conditions of the devices.

Inverted top-emission organic light emitting devices (TEOLEDs) with a mixed single layer by mixing of electron transport materials (PyPySPyPy and Alq 3 ), hole transport material (α-NPD) and dope material (rubrene) were investigated. Maximum power efficiency of 3.5 lm/W and maximum luminance of 7000 cd/m 2 were obtained by optimizing the mixing ratio of PyPySPyPy:Alq 3 :α-NPD:rubrene=25:50:25:1. Luminance and power efficiency of mixed single layer device were two times improved compared to bi-layer heterojunction device and tri-layer heterojunction device. Lifetime test also shows that the mixed single layer device exhibits longer operational lifetimes of 343 h, which is three times longer than the 109 h for tri-layer device, and two times longer than the 158 h for bi-layer device. In addition, the maximum luminance and power efficiency were obtained at 20,000 cd/m 2 and 7.5 lm/W, respectively, when a TPD layer of 45 nm was capped onto the top metal electrode.

PurposeTo establish the effects of TSH stimulation on the uptake of fluorine-18-labeled 2-fluoro-2-deoxy-d-glucose for differentiated thyroid carcinoma (DTC) with thyroglobulin-positive and scan negative metastases.Materials and methodsWe searched the MEDLINE, EMBASE and the Cochrane Library for prospective controlled trials using TSH stimulation as an intervention. The outcomes of positron emission tomography (PET)-positive lesions, tumor-to-background ratio, maximum standard uptake value of the detected lesions were extracted and synthesized, and patients with the altered clinical management were studied. A meta-analysis was carried out using the Review Manager software.ResultsSeven prospective controlled clinical trials with 168 patients were found. All studies had a low risk of bias. PET scans under TSH stimulation versus thyroid hormone suppression showed statistically significant differences in the number of patients with PET true-positive lesions (odds ratio (OR) 2.45, 95% confidence interval (CI) 1.23–4.90) and in the number of the PET-detected lesions (OR 4.92, 95% CI 2.70–8.95) and tumor-to-background ratios. PET scans taken under TSH stimulation altered clinical management in altogether 12/130 (9%) patients in five paired studies (OR 2.40, 95% CI 1.11–5.22).ConclusionThe data indicate that TSH stimulation should be recommended for DTC patients undergoing PET scanning in these circumstances. However, further well-designed studies emphasizing on the clinical significance of altered management by PET under TSH stimulation are needed.

Transparent p-type nickel oxide (NiO) thin films have been epitaxially grown on (0001) Al2O3 substrates by a chemical solution method of polymer-assisted deposition for the first time. The films have a high optical transparency of above 95% in the wavelength range of 350-900 nm.

The authors demonstrate a pentacene/C60 heterojunction organic solar cell utilizing MoO3-doped pentacene thin films as an interfacial layer at anode and a multicharge-separation layer between pentacene and C60, respectively. The short-circuit current density and the open-circuit voltage were improved simultaneously compared with the reference device, resulting in an improvement in power conversion efficiency from 0.97% to 2.29%. Absorption spectra measurement, surface morphology analysis, and interfacial evaluation at anode side in the hole-dominant devices were carried out to reveal the functions of MoO3-doped pentacene films in OSCs.

Measurements of the current density–voltage (J–V) characteristics of a poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 (PCBM)-based electron-dominated device as functions of temperature were carried out. A transport transition from three-dimensional variable range hopping (VRH) to space-charge-limited current (SCLC) with an exponential distribution of traps (filled and unfilled) was observed. The bulk trap density, about 1018 cm-3, of the P3HT:PCBM blend film was evaluated by the differential method. A shift to the lowest unoccupied molecular orbital (LUMO) state of PCBM for trap density distribution was observed owing to the temperature dependence of the Fermi level of PCBM materials. It is supposed that the Fermi level of PCBM materials is strongly temperature-dependent similarly to that of amorphous silicon semiconductors.

We report on the enhanced carrier injection in pentacene thin-film transistors with a thin MoO3-doped pentacene layer between pentacene semiconductor and the source-drain electrodes. Device performance including drain current, field effect mobility, and threshed voltage are improved by employing a MoO3-doped pentacene thin layer. The barrier height at the Au/pentacene interface is lowered from 0.12 to 0.05 eV after inserting a MoO3-doped pentacene thin layer between them. The reduced barrier height is attributed to the formation of a good contact between MoO3-doped pentacene and Au owing to smoothed surface morphology of pentancene and suitable band bending by MoO3 doping.

A highly simplified single layer solution-processed phosphorescent organic light emitting device (PHOLED) with the maximum ηP 11.5 lm/W corresponding to EQE 9.6% has been demonstrated. The solution-processed device is shown having comparable even exceeding device performance to vacuum-processed PHOLED. The simplified device design strategy represents a pathway toward large area, low cost and high efficiency OLEDs in the future. The charge injection and conduction mechanisms in two solution- and vacuum-processed devices are also investigated by evaluating the temperature dependence of current density – voltage characteristics.

The authors investigate the effects of a small molecular dye, perylene, on the performance of organic solar cells based on poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 (PCBM) blends. The short-circuit current density is improved, and a maximum 27% enhancement in power conversion efficiency is achieved by doping suitable perylene into P3HT:PCBM blends. It is attributed to be the enhanced absorption of perylene doped P3HT:PCBM blends, which is also confirmed in single-carrier devices. Moreover, the barrier height at the anode/blend is largely lowered from 0.61 eV to 0.28 eV through evaluating temperature dependence of current-voltage characteristics.

The authors investigate bias and temperature dependent current density-voltage (J-V) characteristics in solution-processed small molecular mixed single layer organic light emitting devices using Au/MoO3 as hole and Al as electron injection electrode. Hole and electron injections are primarily ascribed to the Schottky thermionic emission mechanism. However, at high field of >9×105 V cm−1, hole transport is found to be bulk trapped corresponding to space charge limited current with an exponential distribution of traps. The bulk trap density, about 1018 cm−3 in mixed organic layer, is evaluated by the differential method.

The authors investigate efficiency roll-off in 5,6,11,12-tetraphenylnaphthacene (rubrene)-based mixed single layer top-emission organic light emitting devices by codoping with special additive dopants. The efficiency roll-off is suppressed after codoping rubrene with phenoxazone (Nile red). Due to dual nature of rubrene acting as electron hopping site and hole trap, it not only captures carrier producing light but also transfers energy to Nile red and then produces light. Meanwhile, Nile red molecules can also get energy from host directly. There exists a competitive process between three emission mechanisms, which depress self-quenching of dye molecules during emission, resulting in improved efficiency and lowered driving voltage.