Due to the difficulty in achieving high efficiency and high color purity simultaneously, blue emission is the limiting factor for the performance and stability of OLEDs. Since 2003, we have been working on organic light-emitting diodes (OLEDs), especially on blue light. After a series of molecular designs, novel strategies have been proposed from different aspects. At first, highly efficient deep blue emission could be achieved through molecular design with highly twisted structure to suppress fluorescence quenching and redshift. Deep blue emitters with high efficiency in solid state, a twisted structure with aggregation induced emission (AIE) characteristics was incorporated to inhibit molecular aggregation, and triplet-triplet fusion (TTF) and hybridized localized charge transfer (HLCT) were adopted to increase the ratio of triplet exciton used. Secondly, a highly efficient blue OLED could be achieved through improving charge transport. New electron transport materials (ETMs) with wide band gap were developed to control charge transport balance in devices. Thirdly, a highly efficient deep blue emission could be achieved through a mesoscopic structure of out-coupling layer. A mesoscopic photonic structured organic thin film was fabricated on the top of metal electrode by self-aggregation in order to improve the light out-coupling efficiency.

Flexible perovskite solar cells (PSCs) were ideal candidates for wearable devices due to the merits of flexibility, high efficiency, and being lightweight, and they could be fabricated in a continuous roll-to-roll production process to achieve large-area and low cost devices. Herein, the high efficiency (up to 18.53%) and fill factor (0.81) of flexible PSCs (ITO/SnO2/KCl/MAPbI(3)/spiro-OMeTAD/Ag) were achieved by low-pressure assisted solution processing under low temperature (<= 100 degrees C). The surface morphology and crystallinity of perovskite films were effectively promoted by the KCl modification and the defect density of perovskite films as well as the hysteresis of the corresponding devices was reduced accordingly. In addition, the stability and bendability of the KCl-modified flexible PSCs were improved simultaneously. To the best of our knowledge, both the efficiency and fill factor are the best among all flexible PSCs reported to date. Therefore, the insertion of KCl between SnO2 and MAPbI(3) layers provided a promising strategy for highly efficient flexible PSCs fabricated in low temperature (<= 100 degrees C) conditions.

The electron-transporting materials (ETMs) with excellent electron injection (EI) and electron transporting properties are prerequisites for highly efficient organic light-emitting diodes (OLEDs). In this work, we report a novel ETM, 2,7-di([3,2 `:6 `,3 `'-terpyridin]-4 `-yl)-9,9 `-spirobifluorene (27-mTPSF), which is synthesized by combining electron-withdrawing terpyridine (TPY) moieties with rigid twisted spirobifluorene. This rigid twisted structure helps to maintain the morphological stability of the amorphous film and contributes to the enhancement of the device lifetime. The nitrogen atom at the meta-position on the peripheral pyridine in 27-mTPSF can enhance the horizontal molecular orientation and the electron-transporting property. A green phosphorescent OLED (PhOLED) based on tris[2-(p-tolyl)pyridine]iridium(iii) (Ir(mppy)(3)) as the emitter and 27-mTPSF as ETM displayed a maximum external quantum efficiency (EQE) of 23.1%, and a half-life (T-50) of 77, 4330 and 243 495 h at an initial luminance of 10 000, 1000 and 100 cd m(-2), respectively, which are significantly superior to those of the device based on the conventional ETM 1,3,5-tris(N-phenylbenzimid azol-2-yl-benzene (TPBi). These results indicate a potential application for the ``(A)(n)-D-(A)(n)'' structured terpyridine ETMs.

We studied temperature-dependent amplified spontaneous emission (ASE) in CsPbBr3 perovskite thin films. For temperatures 180-360 K, a narrow-band lasing is observed. However, a new accompanying ASE band appears below 180 K, indicating a more complicated behavior. The two ASE bands are strongly correlated and in competition; they are assigned as exciton and bi-exciton recombination. We estimated the exciton binding energy (E-B = 27.3 meV) and that of the bi-exciton, which is lower than the E-B. The reduced effective mass of the exciton is estimated as mu = 0.11 m(c). This discovery identifies more details of the ASE phenomenon. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

The electron-transporting materials (ETMs) with excellent electron injection (EI) and electron transporting properties are prerequisites for highly efficient organic light-emitting diodes (OLEDs). In this work, we report a novel ETM, 2,7-di([3,2 `:6 `,3 `'-terpyridin]-4 `-yl)-9,9 `-spirobifluorene (27-mTPSF), which is synthesized by combining electron-withdrawing terpyridine (TPY) moieties with rigid twisted spirobifluorene. This rigid twisted structure helps to maintain the morphological stability of the amorphous film and contributes to the enhancement of the device lifetime. The nitrogen atom at the meta-position on the peripheral pyridine in 27-mTPSF can enhance the horizontal molecular orientation and the electron-transporting property. A green phosphorescent OLED (PhOLED) based on tris[2-(p-tolyl)pyridine]iridium(iii) (Ir(mppy)(3)) as the emitter and 27-mTPSF as ETM displayed a maximum external quantum efficiency (EQE) of 23.1%, and a half-life (T-50) of 77, 4330 and 243 495 h at an initial luminance of 10 000, 1000 and 100 cd m(-2), respectively, which are significantly superior to those of the device based on the conventional ETM 1,3,5-tris(N-phenylbenzimid azol-2-yl-benzene (TPBi). These results indicate a potential application for the ``(A)(n)-D-(A)(n)'' structured terpyridine ETMs.

INTRODUCTION Smoking cessation should be part of tuberculosis (TB) treatment, but a cessation service is not available as part of a routine TB service in most low- and middle-income countries. WHO and The International Union Against Tuberculosis and Lung Disease (The Union) issued a guideline and China implemented a pilot project 5 years ago. This study aimed to determine changes in smoking status among TB patients at 5 years after completion of anti-TB treatment to observe long-term outcome of a smoking cessation project whose baseline characteristics were associated with a relapse of smoking behavior. METHODS A prospective longitudinal study was conducted 5 years after completion of anti-TB treatment to assess changes in patient smoking status against individual baseline data that were entered into a database at the time of TB registration. The patients were tracked by trained village doctors and validated by township health staff. Their smoking status was assessed and entered into the database and analysed. RESULTS Of the 800 TB patients registered at baseline, 650 (81.2%) were tracked. Ninety-one (11.4%) patients died and 59 (7.4%) were lost to follow-up. The rates of remaining non-smoking after 5 years were 82.0%, 63.0%, 49.6%, 43.5% and 30.0%, respectively for non-smokers, ex-smokers, current smokers who received cessation intervention, recent quitters, and current smokers not on a cessation intervention. The odds of smoking relapse were significantly higher for those aged >= 65 years (p=0.003) and registered in Xingguo County (p=0.025). CONCLUSIONS Findings from this study confirmed that non-smokers, ex-smokers and current smokers who received cessation intervention at baseline maintained higher non-smoking rates compared with those who did not receive the intervention. To prevent relapse, intensive cessation support should be given to TB patients aged >= 65 years. TB programme managers need to ensure integration and provision of smoking cessation advice and smoke-free policy in routine TB services.

All-inorganic CsPbI2Br perovskite has attracted increasing attention, owing to its outstanding thermal stability and suitable bandgap for optoelectronic devices. However, the substandard power conversion efficiency (PCE) and large energy loss (E-loss) of CsPbI2Br perovskite solar cells (PSCs) caused by the low quality and high trap density of perovskite films still limit the application of devices. Herein, the post-treatment of evaporating cesium bromide (CsBr) is utilized on top of the perovskite surface to passivate the CsPbI2Br-hole-transporting layer interface and reduce E-loss. The results of microzone photoluminescence indicate that the evaporated CsBr gathered at the grain boundaries of CsPbI2Br layers and Br-enriched perovskites (CsPbIxBr3-x, x < 2) are formed, which can provide protection for CsPbI2Br. Therefore, the gaps between crystal grains are filled up, and the recombination loss of the all-inorganic CsPbI2Br PSCs is reduced accordingly. The champion device exhibits high open-circuit voltage and a PCE of 1.271 V and 16.37%, respectively. This is the highest reported PCE among all-inorganic CsPbI2Br PSCs reported so far. In addition, the stability of CsPbI2Br PSCs is effectively improved by CsBr passivation, and the device without encapsulation can retain 86% of its initial PCE after 1368 h of storage, which is beneficial for practical applications.

Interface modification engineering has been widely used as a flexible and effective method to optimize the performance of perovskite photovoltaic devices. Herein, we adopt NiCl2 as a modifier to passivate the interface at the electron transporting layer (ETL) and perovskite layer to drive high-efficiency perovskite solar cells (PSCs) with increased open circuit voltage (V-oc) and neglectable hysteresis. The devices based on SnO2/NiCl2 ETL achieved a high V-oc (1.17 V) and power conversion efficiency (PCE) (19.46%). The improvement is attributed to the increased energy level of the conduction band minimum (E-CBM) and reduced defect states by NiCl2 interface modification. Our findings provide an effective way to obtain higher V-oc and PCE values as well as neglectable hysteresis for planar PSCs.

Compared with silicon-based solar cells, organic-inorganic hybrid perovskite solar cells (PSCs) possess a distinct advantage, i.e., its application in the flexible field. However, the efficiency of the flexible device is still lower than that of the rigid one. First, it is found that the dense formamidinium (FA)-based perovskite film can be obtained with the help of N-methyl-2-pyrrolidone (NMP) via low pressure-assisted method. In addition, CH3NH3Cl (MACl) as the additive can preferentially form MAPbCl(3-)(x)I(x) perovskite seeds to induce perovskite phase transition and crystal growth. Finally, by using FAI center dot PbI2 center dot NMP+x%MACl as the precursor, i.e., ligand and additive synergetic process, a FA-based perovskite film with a large grain size, high crystallinity, and low trap density is obtained on a flexible substrate under ambient conditions due to the synergetic effect, e.g., MACl can enhance the crystallization of the intermediate phase of FAI center dot PbI2 center dot NMP. As a result, a record efficiency of 19.38% in flexible planar PSCs is achieved, and it can retain about 89% of its initial power conversion efficiency (PCE) after 230 days without encapsulation under ambient conditions. The PCE retains 92% of the initial value after 500 bending cycles with a bending radii of 10 mm. The results show a robust way to fabricate highly efficient flexible PSCs.

Due to the difficulty in achieving high efficiency and high color purity simultaneously, blue emission is the limiting factor for the performance and stability of OLEDs. Since 2003, we have been working on organic light-emitting diodes (OLEDs), especially on blue light. After a series of molecular designs, novel strategies have been proposed from different aspects. At first, highly efficient deep blue emission could be achieved through molecular design with highly twisted structure to suppress fluorescence quenching and redshift. Deep blue emitters with high efficiency in solid state, a twisted structure with aggregation induced emission (AIE) characteristics was incorporated to inhibit molecular aggregation, and triplet-triplet fusion (TTF) and hybridized localized charge transfer (HLCT) were adopted to increase the ratio of triplet exciton used. Secondly, a highly efficient blue OLED could be achieved through improving charge transport. New electron transport materials (ETMs) with wide band gap were developed to control charge transport balance in devices. Thirdly, a highly efficient deep blue emission could be achieved through a mesoscopic structure of out-coupling layer. A mesoscopic photonic structured organic thin film was fabricated on the top of metal electrode by self-aggregation in order to improve the light out-coupling efficiency.

Flexible perovskite solar cells (PSCs) were ideal candidates for wearable devices due to the merits of flexibility, high efficiency, and being lightweight, and they could be fabricated in a continuous roll-to-roll production process to achieve large-area and low cost devices. Herein, the high efficiency (up to 18.53%) and fill factor (0.81) of flexible PSCs (ITO/SnO2/KCl/MAPbI(3)/spiro-OMeTAD/Ag) were achieved by low-pressure assisted solution processing under low temperature (<= 100 degrees C). The surface morphology and crystallinity of perovskite films were effectively promoted by the KCl modification and the defect density of perovskite films as well as the hysteresis of the corresponding devices was reduced accordingly. In addition, the stability and bendability of the KCl-modified flexible PSCs were improved simultaneously. To the best of our knowledge, both the efficiency and fill factor are the best among all flexible PSCs reported to date. Therefore, the insertion of KCl between SnO2 and MAPbI(3) layers provided a promising strategy for highly efficient flexible PSCs fabricated in low temperature (<= 100 degrees C) conditions.

Organic-inorganic metal halide perovskites have drawn a great deal of attention due to their supreme optical and electrical properties and their potential in future application in optoelectronic devices. Here, we carry out finite-difference time-domain (FDTD) simulation on different experimentally realistic structures of perovskite solar cells (PSC) and optimize their parameters with assistance of neural network (NN). We find an optimized structure with 30.48% enhancement comparing to planar structure and the fact that with properly design, 300-nm-thick nano-textured structure can outperform 900-nm-thick planar structure. We believe that light trapping structure is essential in thin film PSCs and also has a great potential in lead-free PSCs.

High efficiency organic-inorganic hybrid perovskite solar cells have attracted significant attention and experienced a rapid development in recent years. Lithium-doped spiro-OMeTAD is one of the most commonly used hole transporting material, however, the hygroscopicity of lithium dopant usually causes serious moisture instability of devices. Herein, we demonstrate a dopant-free spiro-OMeTAD as hole transporting layer to improve the ambient stability of planar perovskite solar cells. With the optimization of the thickness of spiro-OMeTAD layer, the dopant-free spiro-OMeTAD based device achieved a comparable device performance with a champion power conversion efficiency of 16.92%. Moreover, the unencapsulated dopant-free device showed significantly improved stability, which still maintained 95% of its initial efficiency after storage in ambient environment for 60 days. This work provides a simple and valid approach to overcome the instability issue of spiro-OMeTAD based devices, paving a way to manufacture more stable and efficient perovskite photovoltaics.

Interfacial modification as a feasible strategy to improve the properties of perovskite solar cells (PSCs) has been widely studied in recent years. In this work, PbCl2 modification at the interface of SnO2/CH3NH3PbI3 was used for CH3NH3PbI3-based planar PSCs. The introduction of PbCl2 between SnO2 and CH3NH3PbI3 layers boosted the crystallization of perovskite film, which promoted the photovoltaic properties of corresponding PSCs. The open circuit voltage (VOC) and fill factor (FF) of the PbCl2-modified devices (1 mg/mL) were 1.11 V and 0.79, respectively, which were both higher than those of the reference devices without PbCl2 (1.04 V and 0.76). Moreover, a steady-state power output efficiency exceeding 19% was obtained for the PbCl2-modified devices (1 mg/mL), which implied that PbCl2 modification was an effective and low cost strategy for efficient PSCs.

Cs2AgBiBr6 having a double perovskite structure is expected to achieve non-lead and stable optoelectronic devices, and has received wide attention recently. A strategy for improving of perovskite films via Rubidium cation (Rb+) is for the first time reported. When Rb+ was incorporated into Cs2AgBiBr6 to form (Cs1-xRbx)(2)AgBiBr6, the absorption at long wavelength was enhanced and the density of defect state was reduced without changing the crystal lattice. Furthermore, the mechanism of Rb+ doping to improve double perovskites and the optimal doping ratio was studied in this report. The average power conversion efficiency of doped devices is nearly 15% higher than that of standard devices from 20 devices of each group. Moreover, in the champion device, the power conversion efficiency achieved 1.52% with a high fill factory of 0.788.

The performance of perovskite solar cells (PSCs) depends on the crystallization of the perovskite layer. Herein, we demonstrate an effective photoannealing (PA) process by a halogen lamp. During the PA process, on the one hand, the lower energy photon, that is, near IR up to similar to 1015 nm photon, drives the crystallization of the perovskite film, similar to the conventional thermal annealing (TA). On the other hand, the higher energy photon of PA can excite the trapped carriers and release the space charges, thus leading to an ideal perovskite layer with better crystallinity and lower density of defect when compared to that of TA. A maximum power conversion efficiency (PCE) has been obtained to be 20.41% in the CH3 NH3 PbI3 -based planar PSCs based on PA because of the increase of J(sc) and V-oc, much higher than the control device based on the conventional TA with a maximum PCE of 18.08%. Therefore, this result demonstrates that PA is an effective method to promote the device performances and reduce the fabrication cost, which provides a potential approach for the commercial application of perovskite devices.

Silver bismuth iodide (Ag-Bi-I) as an environmentally friendly semiconductor with suitable band gap and high stability has been regarded as a potential photovoltaic material, while the reported mesoscopic devices all showed poor open circuit voltage (V-oc) of 0.5-0.6 V. Here, we successfully fabricated AgBiI4 planar heterojunction solar cells via a solution method with a Voc approaching 0.9 V, in which 2 wt % lithium bis(trifluoromethylsulfonyl)-imide (Li-TFSI) was added into the AgI:BiI3 precursor. The device presents a power conversion efficiency of 2.50 +/- 0.20% with a V-oc of 0.82 +/- 0.20 V. Experimental results indicated that the readily coordinated component in the organic salt, TFSI-, could assist film growth and result in a full coverage morphology. Furthermore, double layer devices showed the carrier separation occurred in the interface of SnO2/AgBiI4. These results indicated interface extraction and film enhancement should be concerned in further improvements.

Flexible perovskite solar cells (PSCs) were ideal candidates for wearable devices due to the merits of flexibility, high efficiency, and being lightweight, and they could be fabricated in a continuous roll-to-roll production process to achieve large-area and low cost devices. Herein, the high efficiency (up to 18.53%) and fill factor (0.81) of flexible PSCs (ITO/SnO2/KCl/MAPbI(3)/spiro-OMeTAD/Ag) were achieved by low-pressure assisted solution processing under low temperature (<= 100 degrees C). The surface morphology and crystallinity of perovskite films were effectively promoted by the KCl modification and the defect density of perovskite films as well as the hysteresis of the corresponding devices was reduced accordingly. In addition, the stability and bendability of the KCl-modified flexible PSCs were improved simultaneously. To the best of our knowledge, both the efficiency and fill factor are the best among all flexible PSCs reported to date. Therefore, the insertion of KCl between SnO2 and MAPbI(3) layers provided a promising strategy for highly efficient flexible PSCs fabricated in low temperature (<= 100 degrees C) conditions.

High-efficiency organic-inorganic hybrid perovskite solar cells have experienced rapid development and attracted significant attention in recent years. However, instability to an ambient environment such as moisture is a facile challenge for the application of perovskite solar cells. Herein, 1,8-octanediammonium iodide (ODAI) is employed to construct a two-dimensional modified interface by in situ combined with residual PbI2 on the formamidinium lead iodide (FAPbI(3)) perovskite surface. The ODA(2+ )ion seems to lie horizontally on the surface of a three-dimensional perovskite due to its substitution for two FA(+) ions, which could protect the bulk perovskite more effectively. The unencapsulated perovskite solar cells showed notably improved stability, which remained 92% of its initial efficiency after storing in an ambient environment for 120 days. In addition, a higher open-circuit voltage of 1.13 V compared to that of the control device (1.04 V) was obtained due to the interface energy level modification and defect passivation. A champion power conversion efficiency of 21.18% was therefore obtained with a stabilized power output of 20.64% at the maximum power point for planar perovskite solar cells.

Perovskite solar cells (PSCs) have been paid more attention because of its high power conversion efficiency (PCE) and flexible applications. Low temperature process for PSCs is critical for high performance flexible devices and industrial applications. Herein, the photovoltaic properties of the PSCs based on a polyelectrolyte interfacial layer of polyethyleneimine (PEI) were studied in this work and the configuration of PSCs was indium fin oxide (ITO)/PEI/SnO2/perovskite/spiro-OMeTAD/Ag. Due to the spin-coated PEI on ITO substrates, smooth cathodes (ITO/PEI) with low work function were obtained and the champion PCE of 19.36% and 16.81% for the rigid and flexible devices respectively was achieved accordingly. Moreover, the PCE of the rigid and flexible PSCs with PEI (0.1 mg mL(-1)) remained similar to 95% and similar to 90% of the initial values respectively after 80 days in ambient conditions. Meanwhile, the PCE of the flexible PSCs based on PEI (0.1 mg mL(-1)) remained 85% of the initial value after 100 bending cycles and the bendability of the flexible PSCs was improved accordingly. All the experimental data implied that the fabrication of PEI onto ITO electrodes was an effective way to promote the photovoltaic properties of the low-temperature processed rigid and flexible PSCs.