One grand challenge for long-lived perovskite solar cells is that the common electrode materials in solar cells, such as silver and aluminum or even gold, strongly react with hybrid perovskites. Here ...we report the evaluation of the potential of copper (Cu) as the electrode material in perovskite solar cells for long-term stability. In encapsulated devices which limit exposure to oxygen and moisture, Cu in direct contact with CH3NH3PbI3 showed no reaction at laboratory time scales, and is predicted to be stable for almost 170 years at room temperature and over 22 years at the nominal operating cell temperature of 40 degree C. No diffusion of Cu into CH3NH3PbI3 has been observed after thermal annealing for over 100 hours at 80 degree C, nor does Cu cause charge trap states in direct contact with CH3NH3PbI3 after long-term thermal annealing or illumination. High performance devices with efficiency above 20% with a Cu electrode retain 98% of the initial efficiency after 816 hours storage in an ambient environment without encapsulation. The results indicate Cu is a promising low-cost electrode material for perovskite solar cells for long-term operation.
We report here a simple, high-yield yet low-cost approach to design single-layer MoS2 nanosheets with controllable size via an improved oleum treatment exfoliation process. By decorating MoS2 ...nanosheets with chitosan, these functionalized MoS2 nanosheets have been developed as a chemotherapeutic drug nanocarrier for near-infrared (NIR) photothermal-triggered drug delivery, facilitating the combination of chemotherapy and photothermal therapy into one system for cancer therapy. Loaded doxorubicin could be controllably released upon the photothermal effect induced by 808 nm NIR laser irradiation. In vitro and in vivo tumor ablation studies demonstrate a better synergistic therapeutic effect of the combined treatment, compared with either chemotherapy or photothermal therapy alone. Finally, MoS2 nanosheets can also be used as a promising contrast agent in X-ray computed tomography imaging due to the obvious X-ray absorption ability of Mo. As a result, the high-throughput oleum treatment exfoliation process could be extended for fabricating other 2D nanomaterials, and the NIR-triggered drug release strategy was encouraging for simultaneous imaging-guided cancer theranostic application.
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Here, we present a precision cancer nanomedicine based on Bi2S3 nanorods (NRs) designed specifically for multispectral optoacoustic tomography (MSOT)/X-ray computed tomography (CT)-guided ...photothermal therapy (PTT). The as-prepared Bi2S3 NRs possess ideal photothermal effect and contrast enhancement in MSOT/CT bimodal imaging. These features make them simultaneously act as “satellite” and “precision targeted weapon” for the visual guide to destruction of tumors in vivo, realizing effective tumor destruction and metastasis inhibition after intravenous injection. In addition, toxicity screening confirms that Bi2S3 NRs have well biocompatibility. This triple-modality-nanoparticle approach enables simultaneously precise cancer therapy and therapeutic monitoring.
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The large specific surface area of perovskite nanocrystals (NCs) increases the likelihood of surface defects compared to that of bulk single crystals and polycrystalline thin films. It is thus ...crucial to comprehend and control their defect population in order to exploit the potential of perovskite NCs. This Perspective describes and classifies recent advances in understanding defect chemistry and avenues toward defect density reduction in perovskite NCs, and it does so in the context of the promise perceived in light-emitting devices. Several pathways for decreasing the defect density are explored, including advanced NC syntheses, new surface-capping strategies, doping with metal ions and rare earths, engineering elemental compensation, and the translation of core–shell heterostructures into the perovskite materials family. We close with challenges that remain in perovskite NC defect research.
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Inorganic metal oxide electron‐transport layers (ETLs) have the potential to yield perovskite solar cells with improved stability, but generally need high temperature to form conductive and ...defect‐less forms, which is not compatible with the fabrication of flexible and tandem solar cells. Here, we demonstrate a facile strategy for developing efficient inorganic ETLs by doping SnO2 nanocrystals (NCs) with a small amount of Sb using a low‐temperature solution‐processed method. The electrical conductivity was remarkably enhanced by Sb‐doping, which increased the carrier concentration in Sb:SnO2 NCs. Moreover, the upward shift of the Fermi level owing to doping results in improved energy level alignment, which led to reduced charge recombination, and thus longer electron recombination lifetime and improved open‐circuit voltage (VOC). Therefore, Sb‐doping of SnO2 significantly enhanced the photovoltaic performance of planar perovskite devices by increasing the fill factor and VOC, and reducing photocurrent hysteresis, extending the potential application of low‐temperature‐processed ETLs in future flexible and tandem solar cells.
Doping effect: Sb:SnO2 nanocrystalline films are successfully prepared using a low‐temperature solution‐processed method as an efficient electrontransport layer for planar perovskite solar cells. Intentional Sb‐doping is demonstrated as an effective approach to increase the electrical conductivity and upward shift the Fermi level of SnO2, leading to dramatically enhanced photovoltaic performance and suppressed hysteresis.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Self‐assembled monolayers (SAMs) based on Br‐2PACz (2‐(3,6‐dibromo‐9H‐carbazol‐9‐yl)ethylphosphonic acid) 2PACz (2‐(9H‐Carbazol‐9‐yl)ethylphosphonic acid) and MeO‐2PACz ...(2‐(3,6‐dimethoxy‐9H‐carbazol‐9‐yl)ethylphosphonic acid) molecules were investigated as hole‐extracting interlayers in organic photovoltaics (OPVs). The highest occupied molecular orbital (HOMO) energies of these SAMs were measured at −6.01 and −5.30 eV for Br‐2PACz and MeO‐2PACz, respectively, and found to induce significant changes in the work function (WF) of indium‐tin‐oxide (ITO) electrodes upon chemical functionalization. OPV cells based on PM6 (poly(2,6‐(4,8‐bis(5‐(2‐ethylhexyl‐3‐fluoro)thiophen‐2‐yl)‐benzo1,2‐b:4,5‐b’dithiophene))‐alt‐(5,5‐(1’,3’‐di‐2‐thienyl‐5’,7’‐bis(2‐ethylhexyl)benzo1’,2’‐c:4’,5’‐c’dithiophene‐4,8‐dione)) : BTP‐eC9 : PC71BM (6,6‐phenyl‐C71‐butyric acid methyl ester) using ITO/Br‐2PACz anodes exhibited a maximum power conversion efficiency (PCE) of 18.4 %, outperforming devices with ITO/MeO‐2PACz (14.5 %) and ITO/poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT : PSS) (17.5 %). The higher PCE was found to originate from the much higher WF of ITO/Br‐2PACz (−5.81 eV) compared to ITO/MeO‐2PACz (4.58 eV) and ITO/PEDOT : PSS (4.9 eV), resulting in lower interface resistance, improved hole transport/extraction, lower trap‐assisted recombination, and longer carrier lifetimes. Importantly, the ITO/Br‐2PACz electrode was chemically stable, and after removal of the SAM it could be recycled and reused to construct fresh OPVs with equally impressive performance.
Super SAM: Two self‐assembled monolayers (SAMs; Br‐2PACz and MeO‐2PACz) are investigated as hole‐extracting interlayer in organic photovoltaics and compared against the widely used PEDOT : PSS. Cells based on the ternary bulk‐heterojunction blend PM6 : BTP‐eC9 : PC71BM and ITO/Br‐2PACz as the anode exhibit the highest power conversion efficiency of 18.4 %, outperforming devices with ITO/MeO‐2PACz (14.5 %) and even ITO/PEDOT : PSS (17.5 %).
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We have developed a simple and efficient strategy to fabricate WS2 nanosheets with low toxicity and good water solubility via a liquid exfoliation method by using H2SO4 intercalation and ...ultrasonication. The as-prepared WS2 nanosheets were employed not only as an NIR absorbing agent for photothermal therapy (PTT) but also as a photosensitizer (PS) carrier for photodynamic therapy (PDT) due to their sheet like structure that offers large surface area to load PS molecules. Moreover, singlet-oxygen generation of the PSs-WS2 complex could be finely controlled by NIR irradiation that could manipulate the PSs release behavior from WS2 nanosheets. The synergistic anti-tumor effect of WS2 nanosheets mediated PDT-PTT was also evaluated carefully and the results clearly showed that the efficacy of combined PDT-PTT treatment of cancer cells is significantly higher than those of PDT-only and PTT-only treatment, indicating enhanced efficiency of the combined therapeutic system. In addition, the WS2 could be used as a computed tomography (CT) contrast agent for bio-imaging since W atoms have strong X-ray attenuation ability, making them a multifunctional theranostic platform for simultaneous imaging-guided diagnosis and therapy.
Abstract Engineering design of plasmonic nanomaterials as on-demand theranostic nanoagents with imaging, drug carrier, and photothermal therapy (PTT) functions have profound impact on treatment of ...cancer. Here, a facile ‘one-pot’ template-free hydrothermal route was firstly developed for synthesis of plasmonic oxygen deficiency molybdenum oxide hollow nanospheres functionalized by poly(ethylene glycol) (PEG-MoO3–x HNSs). The as-prepared PEG-MoO3–x HNSs not only have good biocompatibility but also exhibit obvious localized surface plasmon resonance (LSPR) absorption in the near-infrared (NIR) region. Especially, due to its intrinsic mesoporous properties and effective photothermal conversion efficiency upon 808-nm NIR laser irradiation, the PEG-MoO3–x HNSs can be applied as a pH/NIR laser dual-responsive camptothecin (CPT) drug delivery nanoplatform for chemotherapy as well as PTT to cancer cells. A remarkably improved synergistic therapeutic effect to pancreatic (PANC-1) tumor-bearing mice was obtained compared to the result of chemotherapy or PTT alone. Apart from its application for drug delivery, the PEG-MoO3–x HNSs can also be employed as an effective contrast nanoagent for photoacoustic (PAT) imaging because of its high NIR absorption, making it promising as a theranostic nanoagent for PAT imaging-guided chemo-photothermal combinational cancer therapy in the nanomedicine field.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The surface composition of perovskite films is very sensitive to film processing and can deviate from the optimal, which generates unfavorable defects and results in efficiency loss in solar cells ...and slow response speed in photodetectors. An argon plasma treatment is introduced to modify the surface composition by tuning the ratio of organic and inorganic components as well as defect type before deposition of the passivating layer. It can efficiently enhance the charge collection across the perovskite–electrode interface by suppressing charge recombination. Therefore, perovskite solar cells with argon plasma treatment yield enhanced efficiency to 20.4% and perovskite photodetectors can reach their fastest respond speed, which is solely limited by the carrier mobility.
An argon plasma treatment is introduced to modify the surface trap types of halide perovskite, which improves the efficiency of a solar cell to 20.4%. The plasma treatment is shown as being also applicable to modify the perovskite single crystals, which enable the fastest response speed for single‐crystal photodetectors.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Blue-emitting perovskites can be easily attained by precisely tuning the halide ratio of mixed halide (Br/Cl) perovskites (MHPs). However, the adjustable halide ratio hinders the passivation of Cl ...vacancies, the main source of trap states leading to inferior performance of blue MHP light-emitting diodes (LEDs). Here, we report a strategy for passivating Cl vacancies in MHP quantum dots (QDs) using nonpolar solvent-soluble organic pseudohalide n-dodecylammonium thiocyanate (DAT), enabling blue MHP LEDs with greatly enhanced efficiency. Density functional theory calculations reveal that the thiocyanate (SCN–) groups fill in the Cl vacancies and remove electron traps within the bandgap. DAT-treated CsPb(Br x Cl1–x )3 QDs exhibit near unity (∼100%) photoluminescence quantum yields, and their blue (∼470 nm) LEDs are spectrally stable with an external quantum efficiency of 6.3%, a record for perovskite LEDs emitting in the range of 460–480 nm relevant to Rec. 2020 display standards, and a half-lifetime of ∼99 s.
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