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To investigate the effectiveness of long-term Baduanjin and aerobic training on the 10-year risk of atherosclerotic cardiovascular disease in prediabetic patients. This study was single-blind randomized controlled trial. A total of 98 participants with prediabetes were randomly divided into three groups: the BDJ (n = 34), AT (n = 32), and control (n = 32) groups. Participants in the BDJ and AT groups underwent one year of supervised group exercise, consisting of 60 min/session every other day. The primary outcomes were metabolic control and the 10-year risk of ASCVD. The secondary outcome was a change in blood glucose status. After the intervention, various metabolic indexes were significantly improved in the two exercise groups relative to the control group and baseline measurements (p < 0.05). Compared with no exercise, BDJ and AT had significant preventive and protective effects against the risk of ASCVD in patients with prediabetes (p < 0.001). The overall effects of the two exercise groups were similar (p > 0.05). Long-term BDJ training can effectively reduce the risk of type 2 diabetes mellitus (T2DM) and its cardiovascular complications in prediabetic patients. The effect of BDJ is similar to that of moderate-intensity aerobic exercise. [ABSTRACT FROM AUTHOR]

The perovskite solar cell has emerged rapidly in the field of photovoltaics as it combines the merits of low cost, high efficiency, and excellent mechanical flexibility for versatile applications. However, there are significant concerns regarding its operational stability and mechanical robustness. Most of the previously reported approaches to address these concerns entail separate engineering of perovskite and charge-transporting layers. Herein we present a holistic design of perovskite and charge-transporting layers by synthesizing an interpenetrating perovskite/electron-transporting-layer interface. This interface is reaction-formed between a tin dioxide layer containing excess organic halide and a perovskite layer containing excess lead halide. Perovskite solar cells with such interfaces deliver efficiencies up to 22.2% and 20.1% for rigid and flexible versions, respectively. Long-term (1000 h) operational stability is demonstrated and the flexible devices show high endurance against mechanical-bending (2500 cycles) fatigue. Mechanistic insights into the relationship between the interpenetrating interface structure and performance enhancement are provided based on comprehensive, advanced, microscopic characterizations. This study highlights interface integrity as an important factor for designing efficient, operationally-stable, and mechanically-robust solar cells. Operational stability and mechanical robustness remain as engineering bottlenecks in perovskite solar cells technology. Here, Dong et al. introduce an interpenetrating perovskite at the electron-transporting-layer interface that enables a 1000-hour stable operation and high endurance against bending fatigue over 2500 cycles. [ABSTRACT FROM AUTHOR]

We show that highly efficient and chromatically stable white organic electroluminescent devices can be obtained, based on two blue emitters with similar structures: 9,10-di-(2-naphthyl)-anthracene (ADN) and 9,10-di-(2-naphthyl)-2-terbutyl-anthracene doped with yellow-orange emitting 5,6,11,12-tetraphenylnaphthacene (rubrene) at ultralow doping concentrations (0.01%–0.05%). The relative intensity of the blue and orange-yellow emissions could be fine-tuned by varying the doping concentrations of rubrene in the host to achieve pure white emission. The energy-transfer mechanism of ADN and rubrene with ultralow doping concentrations is discussed in terms of the long exciton diffusion distance of ADN. [ABSTRACT FROM AUTHOR]

Although perovskite solar cells exhibit excellent power conversion efficiency, the poor stability toward electrical fields and the typically observed device hysteresis phenomenon severely restrict their applications. Ionic migration comes from the migration of halogen from lattice points to halogen vacancies. Considering the strong built-in potential located at the interface between perovskite and carrier transport layers, here we propose that it is the ionic migration at the interfacial depletion region that dominates device hysteresis. The most effective way to achieve hysteresis-free devices is to passivate ionic migration at the interface rather than within perovskite films. We utilized Cs4SnO4 as a modification layer, which could effectively suppress the defects at the interface and thus eliminate hysteresis, as well as shift the conduction band of perovskite/SnO2 closer and decrease the band misalignment. In addition, the partial diffusion of Cs+ into (FAPbI3)0.85(MAPbBr3)0.15 is beneficial for phase stability toward long-term light illumination. Hence, we believe this paper provides a new understanding about the ionic migration process within perovskite solar cells, and Cs4SnO4 modification is an effective and also general method to overcome the device hysteresis issue. [ABSTRACT FROM AUTHOR]

Lighting accounts for one-fifth of global electricity consumption1. Single materials with efficient and stable white-light emission are ideal for lighting applications, but photon emission covering the entire visible spectrum is difficult to achieve using a single material. Metal halide perovskites have outstanding emission properties2,3; however, the best-performing materials of this type contain lead and have unsatisfactory stability. Here we report a lead-free double perovskite that exhibits efficient and stable white-light emission via self-trapped excitons that originate from the Jahn-Teller distortion of the AgCl6 octahedron in the excited state. By alloying sodium cations into Cs2AgInCl6, we break the dark transition (the inversion-symmetry-induced parity-forbidden transition) by manipulating the parity of the wavefunction of the self-trapped exciton and reduce the electronic dimensionality of the semiconductor4. This leads to an increase in photoluminescence efficiency by three orders of magnitude compared to pure Cs2AgInCl6. The optimally alloyed Cs2(Ag0.60Na0.40)InCl6 with 0.04 per cent bismuth doping emits warm-white light with 86 ± 5 per cent quantum efficiency and works for over 1,000 hours. We anticipate that these results will stimulate research on single-emitter-based white-light-emitting phosphors and diodes for next-generation lighting and display technologies. [ABSTRACT FROM AUTHOR]

Preparation of high-quality amorphous oxide semiconductor (AOS) films by wet chemical routes at low temperature (＜100 °C) remains difficult. Here, we conducted systematic research for the low-temperature fabrication of AOS by a solution route using amorphous NbOx as an example. Perovskite solar cells (PSCs) based on a solution-processed amorphous ETL obtain a high power conversion efficiency of up to 19.09%, which is much higher than that of the PSCs using solution-processed AOS ETLs and even compare favourably with those using vacuum-processed ETLs. [ABSTRACT FROM AUTHOR]

Abstract: Recently, the stability of organic–inorganic perovskite thin films under thermal, photo, and moisture stresses has become a major concern for further commercialization due to the high volatility of the organic cations in the prototype perovskite composition (CH3NH3PbI3). All inorganic cesium (Cs) based perovskite is an alternative to avoid the release or decomposition of organic cations. Moreover, substituting Pb with Sn in the organic–inorganic lead halide perovskites has been demonstrated to narrow the bandgap to 1.2–1.4 eV for high‐performance perovskite solar cells. In this work, a series of CsPb1−xSnxIBr2 perovskite alloys via one‐step antisolvent method is demonstrated. These perovskite films present tunable bandgaps from 2.04 to 1.64 eV. Consequently, the CsPb0.75Sn0.25IBr2 with homogeneous and densely crystallized morphology shows a remarkable power conversion efficiency of 11.53% and a high Voc of 1.21 V with a much improved phase stability and illumination stability. This work provides a possibility for designing and synthesizing novel inorganic halide perovskites as the next generation of photovoltaic materials. [ABSTRACT FROM AUTHOR]

Biaxially-extended octithiophene-based conjugated polymers are demonstrated as effective polymeric hole-transporting layers (HTLs) to simultaneously enhance the efficiency and UV-photostability of perovskite solar cells (PVSCs). The intense UV absorption contributed from the conjugated side-chain groups of such polymers facilitated its function of UV filtering when serving as the bottom HTL in PVSCs. Through rationally tailoring polymer backbone structure, a highly efficient (PCE: 18.34%) PVSC with much improved UV-photostability and ambient stability was successfully achieved. [ABSTRACT FROM AUTHOR]

Currently the performance of inverted perovskite solar cells is still lower than that of normal structured devices, due to the imperfect band alignment between the perovskite and hole transport layer (NiO). Herein, we found that the presence of oxygen during film preparation could lower the Fermi level of NiO and decrease the energy mismatch between the perovskite and NiO. The decreased mismatch benefited the VOC of the devices as well as the charge transfer between NiO and the perovskite. In addition, the utilization of Cs–MA–FA mixed ion-based perovskites as absorbers could increase the light response range and improve the thermal and moisture stabilities of perovskite solar cells. Finally, we achieved a stable performance output of 19.2% for inverted planar perovskite solar cells without any hysteresis. [ABSTRACT FROM AUTHOR]

Organometal halide perovskites are emerging as potential materials for light-emitting diodes (LEDs) and lasers due to their superior color purity, tunable band gaps, low cost and solution processability. However, the performance of perovskite LEDs (PeLEDs) is intrinsically limited by the poor morphology and undesirable trap states of the perovskite film, resulting in electric losses. Herein, we demonstrate a unique strategy to obtain high quality perovskite films through the integrated utilization of solvent engineering and moisture exposure. The synergistic effects of solvent engineering and moisture exposure could contribute to uniform and dense morphology meanwhile significantly reducing the trap density of the perovskite films. Strikingly, the controlled exposure to a relative humidity (RH) around 65% significantly improved the photoluminescence lifetime of the formamidinium lead iodide (FAPbI3) film with α/δ phase junction from 14 ns to 35 ns. For the first time, we revealed that moisture treatment could be exploited in PeLEDs for significantly decreasing the trap density of perovskite films, thus enabling a fortyfold increase of external quantum efficiency from 0.03% up to 1.20% as well as a low turn-on voltage at 2.4 V. It is anticipated that this approach could be extended from FAPbI3 to other compositional perovskites and provide guidelines for optimum combination of moisture post-treatment to realize high-performance perovskite devices. [ABSTRACT FROM AUTHOR]

The compositional perovskites have attracted broad attention due to the improved photovoltaic performance and enhanced stability compared with the single cation perovskite, such as methylammonium lead iodide and formamidinium lead iodide. In this study, the moisture stability of the widely used cesium and bromide-containing mixed perovskites is carefully studied by characterizing the morphology, crystallization, and device performance before and after the exposure to moisture. Though the mixed perovskites possess strong resistance to moisture in the ambient air, a rapid degradation is observed when the perovskites are exposed to a high relative humidity (RH) up to 70%. The degradation is evidenced by the obvious appearance of CsPbI3 phase along with needle-like morphology after several hours' storage in 70% RH. Moreover, to suppress the erosion of perovskites by the high-level moisture, an interfacial engineering is introduced with phenylethylammonium iodide (PEAI). The PEAI passivation not only shows a retarded degradation but also delivers an enhanced photovoltaic performance from 13% to >17% with much improved stability under high-level moisture. The results imply the efficacy of interfacial engineering in fabricating high-efficiency and stable perovskite solar cells. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) have recently demonstrated high efficiencies of over 22%, but the thermal stability is still a major challenge for commercialization. In this work, the thermal degradation process of the inverted structured PSCs induced by the silver electrode is thoroughly investigated. Elemental depth profiles indicate that iodide and methylammonium ions diffuse through the electron-trasnporting layer and accumulate at the Ag inner surface. The driving force of forming AgI then facilitates the ions extraction. Variations on the morphology and current mapping of the MAPbI3 thin films upon thermal treatment reveal that the loss of ions occurs at the grain boundaries and leads to the reconstruction of grain domains. Consequently, the deteriorated MAPbI3 thin film, the poor electron extraction, and the generation of AgI barrier result in the degradation of efficiencies. These direct evidences provide in-depth understanding of the effect of thermal stress on the devices, offering both experimental support and theoretical guidance for the improvement on the thermal stability of the inverted PSCs. [ABSTRACT FROM AUTHOR]

The stability of single-crystalline/monocrystalline-like perovskite film is expected to be better than its microcrystalline counterparts. In the present work, highly orientated perovskite thin films (CH3NH3PbI3- xCl x) are prepared by means of aquointermediates assisted solution process. It displays super-duper preferred-orientation along <110> direction that is close to the single crystal, and its diffraction intensity ratio of (110)/(310) is nearly two orders of magnitude higher in contrast to the films that prepared by traditional way. Owing to its superior performances, e.g., highly crystallized quality, stress-free inside films, longer electron lifetime, faster temporal response time, etc., the highly orientated perovskite-based solar cells accordingly allow realizing high efficiency while improving its thermal stability. [ABSTRACT FROM AUTHOR]

In this work, different from the commonly explored strategy of incorporating a smaller cation, MA+ and Cs+ into FAPbI3 lattice to improve efficiency and stability, it is revealed that the introduction of phenylethylammonium iodide (PEAI) into FAPbI3 perovksite to form mixed cation FAxPEA1-xPbI3 can effectively enhance both phase and ambient stability of FAPbI3 as well as the resulting performance of the derived devices. From our experimental and theoretical calculation results, it is proposed that the larger PEA cation is capable of assembling on both the lattice surface and grain boundaries to form quais-3D perovskite structures. The surrounding of PEA+ ions at the crystal grain boundaries not only can serve as molecular locks to tighten FAPbI3 domains but also passivate the surface defects to improve both phase and moisture stablity. Consequently, a high-performance (PCE:17.7%) and ambient stable FAPbI3 solar cell could be developed. [ABSTRACT FROM AUTHOR]

Correction to: I Scientific Reports i https://doi.org/10.1038/s41598-022-22896-5, published online 11 November 2022 In the original version of this Article Lin Liu was incorrectly affiliated with 'School of Nursing, Shaoyang University, Shaoyang, 422000, Hunan Province, China'. School of Nursing, Shaoyang University, Shaoyang, 422000, Hunan Province, China. [Extracted from the article]

The poor stability of hybrid organic–inorganic perovskite is one of crucial problems limiting the practical application of the perovskite solar cells (PSCs). All-inorganic lead-free perovskite materials, with Cs replacing the organic cations and Sn replacing Pb, have shown great potential in achieving high thermal stability. However, tin-based perovskites have inevitably suffered from severe bulk recombination, attributed to Sn vacancies. In this work, we obtain CsSnIBr2 thin films with low Sn vacancy assisted by the addition of hypophosphorous acid (HPA). The HPA additive here as complexant is demonstrated to be capable of speeding up the nucleation process while inhibiting the formation of Sn4+ during the formation process of CsSnIBr2 thin films. With a mesoscopic architecture, the CsSnIBr2 PSCs exhibit efficiency-loss free in 77 days and remarkably stable power output within 9 hours at high temperatures up to 473 K. [ABSTRACT FROM AUTHOR]

Interfacial engineering is an important method to achieve compact and smooth high-quality perovskite films in a one-step method. In this work, we first demonstrate that lead monoxide (PbO) as an interfacial modification material could convert to perovskite crystal seeds and induce the growth of the CH3NH3PbI3−xClx absorber layer. The introduction of the perovskite crystal seeds resulted in a dramatically enhanced coverage and a large grain size of the perovskite films. The PL lifetime measurements verified reduced trap states of the perovskite thin films and enhanced charge transfer at the TiO2/perovskite interface. With a high quality perovskite thin film, the planar perovskite solar cell showed a remarkably improved power conversion efficiency (PCE) of 17.03%. Moreover, the device with PbO as an interfacial layer exhibited superior UV-stability, maintaining 60% of the initial PCE under intensive UV irradiation for 180 min while the control device was almost exhausted. [ABSTRACT FROM AUTHOR]

The interface modification of perovskite thin films has shown great potential to boost the performance of perovskite solar cells during the last few years. Here we demonstrate that cesium chloride (CsCl) as crystal seeds can markedly enhance the coverage of the CH3NH3PbI3−xClx absorber layer on TiO2 in planar heterojunction solar cells, thus boosting the power conversion efficiency (PCE) to 16.8%, with a fill factor (FF) of 0.79. Also, the introduction of CsCl significantly improved the stability of CH3NH3PbI3−xClx under ultra violet (UV) irradiation, which has been verified by XRD, XPS and SEM measurements. The CsCl-treated devices maintained 70% of the original PCE after a prolonged intensive UV irradiation of 200 min while the untreated devices being almost exhausted. Furthermore, we proposed the mechanism concerning CsCl as the modification layer to improve the UV-induced stability issue of perovskite solar cells. [ABSTRACT FROM AUTHOR]

Methylammonium lead iodide perovskite (MAPbI3) has made a re-entry into the literature nowadays for its extraordinary characteristics, such as high absorption of light, long carrier diffusion length, high carrier mobility, low trap-state density, low surface recombination velocity and ease of attainment. Here, we report a self-powered photodetector based on a CH3NH3PbI3 single crystal by employing asymmetric Au–Al electrodes. The key issue of this photodetector was the metal–semiconductor contacts, owing to the Schottky junction between them. By setting the channel length between the Au–Al electrodes to 30 μm for sufficient electron–hole pair separation and transportation, the device showed good performance under 1 sun illumination. The short-circuit photocurrent density and open-circuit voltage were 6.86 mA cm−2 and 0.7 V, respectively. The photocurrent was almost 2 orders of magnitude larger than that based on a perovskite polycrystalline film with a similar device structure. More importantly, the device could detect the lowest noticeable incident power density down to 1 × 10−8 W cm−2. Under this weak light intensity, the responsivity was as high as 0.24 A W−1 without any bias. The photoresponse also had a broadband ranging from 375 nm to 808 nm accompanied by a fast response speed. [ABSTRACT FROM AUTHOR]

Red-light photodetectors without filters are in urgent need for narrowband applications such as full-color imaging and multi-output visible light communication (VLC). However, their development is hindered by the lack of small-band-gap and narrowband response materials. Without wavelength filters, a new type of photodetector with a simple single-layer architecture is developed, based on a stable small-band-gap squarylium dye and characterized by a detectivity peak at 680 nm and full width at half maximum of 80 nm. The device, which exhibits high stability in air and humid conditions, shows a significantly low dark current of ∼2 nA·cm−2 at −2 V and high specific detectivity of 3.2 × 1012 Jones. The response current ratio of the device to red, green, and blue lights with a luminous flux amplitude ratio of 3:6:1 (standard ratio for white light) is 100:12:1.1. These properties indicate that the squarylium dye red-light photodetectors are promising for VLC and other narrowband optoelectronic applications. [ABSTRACT FROM AUTHOR]

Organolead halide perovskites have attracted extensive attention as light harvesting materials for optoelectronic devices due to their high charge carrier mobility, high photoconversion efficiency, and long charge diffusion length. In this study, we present the first self-powered organolead halide perovskite single crystal photodetector driven by a triboelectric nanogenerator (TENG). A high-performance planar photodetector showing a responsivity of 7.92 A W−1 to white light under a bias of 4 V was fabricated on the (100) facet of a bulk CH3NH3PbI3 perovskite single crystal. Furthermore, we demonstrate a cost-effective approach to the fabrication of a drum-shaped TENG by using two used digital versatile discs (DVDs), which could generate a high output of up to 200 V and 55 μA. By integrating the CH3NH3PbI3 single crystal photodetector with the TENG, the self-powered device exhibited a large responsivity of 196 V (mW cm−2)−1 and a wide detection range from 10 μW cm−2 to 100 mW cm−2. These results provide a new strategy for driving the organolead halide perovskite photodetector with the energy harvested from the environment rather than an external power supply. [ABSTRACT FROM AUTHOR]

Sulfuric acid-treated poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/less-defective reduced graphene oxide (ST-PEDOT:PSS/L-rGO) composite films were prepared via a solution-processing route and used as the counter electrodes of dye sensitized solar cells (DSSCs). These platinum (Pt)- and transparent conductive oxide (TCO)-free counter electrodes exhibited strong catalytic activity and excellent flexibility, showing no obvious change in their sheet resistances after 10000 cycles of bending. The integrated quasi-solid-state DSSC device with a TiO2 nanotube/Ti mesh photoanode and a ST-PEDOT:PSS/L-rGO counter electrode exhibited an energy conversion efficiency ( η) of about 1.8%. It also displayed an excellent mechanical stability and durability after bending for 1000 cycles at a small curvature radius of 10 mm. The high flexibility, low cost and efficient catalytic activity make ST-PEDOT:PSS/L-rGO composite films promising counter electrodes for flexible DSSCs. [ABSTRACT FROM AUTHOR]

The morphology and crystal structure of perovskite films are critical for achieving high-performance perovskite solar cells; however in most cases, the conventional one-step solution deposition method hardly yields a homogeneous perovskite film over a large area, especially for CH3NH3PbI3. Here, we propose a facile and environmentally friendly hexane-assisted one-step solution approach for dense and uniform CH3NH3PbI3 thin films. According to the phase diagram of immiscible liquids, n-hexane was chosen as the assistant solvent to speed-up the evaporation of the main solvent N,N-dimethylformamide (DMF) during the solution deposition process, thus significantly promoting the nucleation and crystallization process of CH3NH3PbI3 perovskite. The as-prepared CH3NH3PbI3 films demonstrated a uniform and dense morphology, and enhanced light absorption in a long-wavelength range. In particular, such n-hexane treatment could help eliminate the residual DMF and greatly improve the thermal stability of the obtained perovskite films. The full solution-processed CH3NH3PbI3 solar cells using n-hexane treatment exhibited a maximum power conversion efficiency of 11.7% and average efficiencies of 11.3 ± 0.4% under standard AM 1.5 conditions in comparison with 7.0 ± 0.4% of the conventional cells. The recombination resistance of the cells increased nearly 5 times by using n-hexane. These results suggest that this hexane-assisted one-step solution approach is promising for controlling the crystallization process of perovskites to achieve high-performance perovskite solar cells. [ABSTRACT FROM AUTHOR]

In meso-superstructured solar cells (MSSCs), the state-of-the-art perovskite acts as both the light harvester and electron transporter due to its ambipolar properties. The inefficient pore filling and infiltration of perovskite directly affect the continuous distribution of perovskite in mesoporous Al2O3, resulting in discontinuous carrier transport in the mesoporous structure and insufficient electron injection to the compact TiO2 layer. Herein, we introduce a simple pre-spin-coating process to improve the infiltration and pore filling of perovskite, which results in higher light absorption and enhanced electron injection, as seen in UV-vis spectra and photoluminescence (PL) spectra, respectively. We first apply time of flight (TOF) experiments to characterize charge transport in MSSCs, and the results reveal that more continuous charge transport pathways are formed with the pre-spin-coating process. This effective method, with ease of processing, demonstrates obviously improved photocurrents, reaching an efficiency as high as 14%, and promotes the application of lead halide perovskite materials in the photovoltaics field. [ABSTRACT FROM AUTHOR]

In recent years, the record efficiency of perovskite solar cells (PSCs) has been updated from 9.7% to 20.1%. However, there has been very little study of the issue of stability, which restricts the outdoor application of PSCs. The issues of the degradation of perovskite and the stability of PSC devices should be urgently addressed to achieve good reproducibility and long lifetimes for PSCs with high conversion efficiency. Without studies on stability, exciting achievements cannot be transferred from the laboratory to industry and outdoor applications. In order to improve their stability, a basic understanding of the degradation process of PSCs in different conditions should be acquired via thorough study. This review summarizes recent studies of the relationship of the chemical stability of PSCs with their environment (oxygen and moisture, UV light, solution process, temperature) and corresponding possible solutions. [ABSTRACT FROM AUTHOR]

Lithium salts have been important additives to the hole-transport materials of solid-state hybrid perovskite solar cells to achieve higher hole mobility. However, the observed intercalation of Li+ into TiO2 was demonstrated to decrease the open-circuit voltage (VOC) of the cells. In this work, spinel lithium titanate Li4Ti5O12 (LTO) was used to alleviate this issue by consuming Li+ prior to the contact of Li+ with TiO2 at the interface between sensitized TiO2 and the hole-transport layer through the chemical insertion of Li+ into LTO. Raman and X-ray photoelectron spectroscopy results confirmed the insertion of Li+ into LTO. A Li+ insertion peak in cyclic voltammetry and an increased density of states of TiO2 revealed the role of LTO as a Li+ separator to protect the TiO2 photoanode, providing the mechanism of VOC increase for LTO modification. Electrochemical impedance spectroscopy revealed that LTO modification markedly reduced carrier recombination, improving the fill factor of the devices. Overall, the conversion efficiencies of the devices were significantly increased with a maximum efficiency of 15.1% by addition of LTO. The strategy of using LTO as a multifunctional modifier broadens the scope of interface engineering in solar cells. [ABSTRACT FROM AUTHOR]

The interface between perovskite and the hole transport layer (HTL) is sensitive to photoelectric conversion properties. However, this study shows that the interface wettability of the HTL solution on a perovskite surface could be improved. To address this problem, graphene oxide (GO) with amphiphilic function was used to form a buffer layer between the perovskite and the HTL. After the GO modification, the contact angles of the HTL solution on the perovskite film decreased to zero degrees. X-ray photoelectron spectroscopy revealed that the GO interacts with the perovskite by forming Pb–O bonds, and Raman spectroscopy analysis revealed that the two-dimensional carbon–carbon bonds absorbed the hole transport material, 2,29,7,79-tetrakis-(N,N-di-p-methoxyphenyl-amine)-9,99-spirobifluorene (Spiro-MeOTAD) viaπ–π interactions. The GO layer improved the contact between the perovskite and HTL, resulting in an enhancement of the short circuit current (JSC). Moreover, using GO as an insulating buffer layer can retard charge recombination in solar cells, as revealed by EIS measured in dark conditions, leading to a significant increase in the open-circuit voltage (VOC) and the fill factor (FF). Consequently, the corresponding average efficiency greatly increased by 45.5%, from 10.0% to 14.5%. Therefore, application of GO as a dual-functional buffer layer on the perovskite layer is a useful strategy for preparing highly efficient hybrid perovskite solar cells. [ABSTRACT FROM AUTHOR]

In this study, the crucial role of perovskites capping layers in the TiO2/CH3NH3PbI3 hybrid solar cells is investigated. The capping layers are realized by controlling the concentration of PbI2 solutions in the sequential deposition process. The morphologies of the active layers are studied by high-resolution scanning electron microscopy (HR-SEM). The amount of perovskites in capping layers increases with the concentration of PbI2 solution, and the coverage of perovskite capping layers on TiO2 films is better developed. Except for the correlation between photocurrents and coverages of perovskite proposed by Snaith, we revealed a more detailed relationship between the photovoltaic performances and perovskite capping layers. It is noteworthy that UV-vis absorption increased with perovskites in capping layers. Moreover, according to the diffuse reflection spectra, light scattering, which is beneficial for the conversion efficiency of photons to electrons by directly preventing most of the incident light from transmitting out, is also enhanced due to both the emergence of larger-size particles in the capping layers and the higher effective dielectric coefficient. All of the aforementioned aspects result in high photocurrents up to 20.6 mA cm -- 2 Efficiency as high as 10.3% is ultimately achieved by a simple control of PbI2 concentration in the sequential deposition process. [ABSTRACT FROM AUTHOR]

Combined post-modification strategy of iodide ligands and wide band gap ZnS layer were employed in quantum dot sensitized solar cells. J–V curves show that the combined post-modification could improve the photoconversion efficiency compared to the single post-modification of ZnS because of the more effective passivation. CdS-sensitized and CdS/CdSe-co-sensitized solar cells both reveal that the assembly structure of QDs/I−/ZnS is more beneficial for the efficiency of solar cells than that of QDs/ZnS/I−. EIS results show that the former structure exhibit higher interface resistance and could suppress electron recombination more powerfully. XPS results reveal that the iodide ligands have different binding energy, which indicates a different coordination state of the iodide atom in these two structures. Finally, 3.28% efficiency and 18.16 mA cm−2 were achieved for CdS/CdSe QDSCs by applying this combined post-modification. [ABSTRACT FROM AUTHOR]

4-tert-Butylpyridine (TBP) has been an important component in hole transport layer for hybrid perovskite solar cells. However, our study shows that TBP can corrode the perovskite absorption layer (CH3NH3PbI3) and interfere with the stability of the solar cells. To address this problem, montmorillonite (MMT) was used to form a buffer layer on top of the hole transport layer. XRD results revealed that TBP was intercalated in the MMT structure and UV-vis spectroscopy analysis revealed that this structure could prevent the corrosion of the CH3NH3PbI3 layer. Moreover, the MMT buffer layer could limit charge recombination in the solar cells. A delayed corrosion led to an increased current density owing to enhanced absorption, while a reduced charge recombination led to an increased fill factor and open voltage circuit values. Consequently, the corresponding efficiency largely increased from 9.0% to 11.9%, with an improvement of 32.2%. Therefore, the application of MMT as a bifunctional buffer coating layer on the hole transport layer is a useful strategy for preparing highly efficient hybrid perovskite solar cells with anti-corrosion and delayed charge recombination properties. [ABSTRACT FROM AUTHOR]

Orange-emitting phosphorescent organic light-emitting diodes (PHOLEDs) are drawing more and more attention; however, high-performance hosts designed for orange PHOLEDs are rare. Here, four indolocarbazole/1, 3, 5-triazine hybrids are synthesized to optimize the singlet and triplet energies, as well as transporting properties, for ideal orange PHOLEDs. By introducing moieties with different electronegativity, a graded reduction of the singlet and triplet energies is achieved, resulting in minimum injection barrier and minimum energy loss. Besides, the charge transporting abilities are also tuned to be balanced on the basis of the bipolar features of those materials. The optimized orange PHOLED shows a maximum external quantum efficiency (EQE) of 24.5% and a power efficiency of 64 lm W-1, both of which are among the best values for orange PHOLEDs. What is more, the efficiency roll-off is extremely small, with an EQE of 24.4% at 1000 cd m-2 and 23.8% at 10 000 cd m-2, respectively, which is the lowest efficiency roll-off for orange PHOLEDs to date, resulting in the highest EQE for orange PHOLEDs when the luminance is above 1000 cd m-2. Besides the balanced charges, the small roll-off is also attributed to the wide recombination zone resulting from the bipolar features of the hosts. [ABSTRACT FROM AUTHOR]