facades, roofs, etc. [1-4] Criteria to evaluate the performance of (semi-)transparent photovoltaic (ST-PV) include power conversion efficiency (PCE), averaged photopic transmittance (APT), and color rendering index (CRI), which indicates how good the original color is retained. [5] Since the light-absorbing and transmittance seem a paradox for PV devices, the light utilization efficiency (LUE), a product of PCE and APT (LUE = PCE × APT), is proposed to judge the performance of ST-PV. [4,5] Considering that the solar energy comprises photons of different energies or wavelengths (including both the visible and invisible photons), an ideal ST-PV device should make full use of the invisible photons to achieve high PCE, while allowing most of the visible photons to penetrate through for sake of high APT and CRI. [6-8] Thereafter, photovoltaic devices with good absorbing selectivity, that is, the ability to selectively absorb the near-infrared (NIR) photons and transmit the visible ones, are highly favored for high-performance ST-PV. Theoretically, the maximum LUE of single-junction ST-PV can reach over 20% with absolute selective absorbing property (Figure 1a). [9] While, the practical record LUE can only reach 5.7%, even with the tandem structure. [10] The huge gap can be attributed to the poor absorbing selectivity of ST-PV. [11-13] Particularly, energy band principle excludes most of the high-efficiency photovoltaic materials for ST-PV application. For example, although the inorganic photovoltaic materials, such as silicon, CIGS, CdTe, GaAs, etc, exhibit excellent performance approaching the S-Q limit and NIR absorbing properties, the energy band principle determines their strong absorption in the visible region (≈0% APT) and thus poor selective absorption. [14-16] As a result, these materials are seldom considered for ST-PV application. Fortunately, the semi-transparent organic photovoltaic (ST-OPV) device seems one exception to break the curse of energy band principle to fulfill good selective absorption. The organic semiconductors typically exhibit vibronic lightabsorbing features, which show peaks and valleys in different absorbing regions. Moreover, their absorption profiles can be easily tailored via modifying the molecular structures, rendering more space to realize good absorption selectivity. [17-20] Indeed, tremendous efforts have been devoted to explore high-performance ST-OPV. Particularly, developing the high-performance low band Semi-transparent organic photovoltaics (ST-OPVs) are promising solar windows for building integration. Improving the light-absorbing selectivity, that is, transmitting the visible photons while absorbing the invisible ones, is a key step toward high-performance ST-OPV. To achieve this goal, the optical properties of the active layer, transparent electrode, and capping layer are comprehensively tailored, and a highly efficient ST-OPV with good absorbing selectivity is demonstrated. First, a numerical method is established to quantify the absorbing selectivity of materials and d...

Developing indium‐tin‐oxide (ITO)‐free flexible organic photovoltaics (OPVs) with upscaling capacity is of great significance for practical applications of OPVs. Unfortunately, the efficiencies of the corresponding devices lag far behind those of ITO‐based rigid small‐area counterparts. To address this issue, an advanced device configuration is designed and fabricated featuring a top‐illuminated structure with ultrathin Ag as the transparent electrode. First, a conjugated polyelectrolyte layer, i.e., PCP‐Li, is inserted to effectively connect the bottom Ag anode and the hole transport layer, achieving good photon to electron conversion. Second, charge collecting grids are deposited to suppress the increased resistance loss with the upscaling of the device area, realizing almost full retention of device efficiency from 0.06 to 1 cm2. Third, the designed device delivers the best efficiency of 15.56% with the area of 1 cm2 on polyimide substrate, representing as the record among the ITO‐free, large‐area, flexible OPVs. Interestingly, the device exhibits no degradation after 100 000 bending cycles with a radius of 4 mm, which is the best result for flexible OPVs. This work provides insight into device structure design and optimization for OPVs with high efficiency, low cost, superior flexibility, and upscaling capacity, indicating the potential for the future commercialization of OPVs.

We study the anharmonic phonon interactions in the single-crystal semiconducting (α) and metal-like (β) van der Waals In2Se3 layers, through the determination and analysis of temperature-dependent Raman spectra and thermal conductivities, supported by first-principles calculations of phonon band structures. Our results indicate strong lattice anharmonicity in β-In2Se3 giving rise to significant phonon peak broadening and a suppressed lattice thermal conductivity and reveal that the anharmonic phonon interactions are the main thermal transport-limiting mechanism in both phases. The low thermal conductivity combined with a large electrical conductivity makes the metal-like β-In2Se3 a potential efficient thermoelectric material.

Delicate design and controllable fabrication of efficient oxygen evolution reaction (OER) electrocatalysts based on earth-abundant elements is a highly desired yet challenging task. Herein, Fe2O3@CuO core–shell nanotube heterostructure in situ grown from copper foam (denoted as Fe2O3@CuO NTs/CF) was first synthesized as an efficient OER electrocatalyst. It has been demonstrated that the unique nanotube morphology provided large electrochemical surface area. Moreover, the electron transfer between Fe2O3 and CuO (electronic interaction) within the heterojunction tuned the electronic structure of Cu and Fe sites which not only improved the electron transfer efficiency but also changed the rate-determining step of OER compared with Fe2O3 or CuO, leading to an enhanced OER kinetics (Tafel slope of 41.07 mV dec–1). Benefiting from the structure engineering and electronic modulation, Fe2O3@CuO NTs/CF exhibits an improved activity with 398 mV overpotential at 100 mA cm–2. This work supplies an efficient strategy for fabricating heterostructure catalyst with tubular morphology and modified electronic structure for OER and other electrochemical applications.

Organic solar cells (OSCs) show great promise for future applications due to their merits of low cost, flexibility, and vivid colors, etc. However, the "conventional" device architecture with a brittle and expensive glass/indium tin oxide (ITO) transparent electrode weakens these potential advantages and restricts it to small areas for high performance. Herein, a device architecture simultaneously combining the advantages of high performance, superior flexibility, diverse colors, and low-cost upscaling production is developed. The device structure features a top-illumination geometry with a thermally evaporated ultrathin Ag film as transparent electrode for ITO replacement. The formation of optical microcavity and high conductance of ultrathin Ag enables high performance for upscaled OSCs. Moreover, this device architecture further enables diverse colors via tuning the TeO 2 layer atop of the ultrathin Ag transparent electrode. This topillumination structure is more tolerant for substrates and enables wider flexible substrates. As a result, the flexible OSCs with upscaled areas of 1.05 cm 2 exhibit a best performance of 13.09% (certified 11.9%) with superior flexibility, diverse colors, representing one of the best ITO-free upscaled flexible OSCs. This work provides a versatile device structure to highlight the merits of OSCs, and paves the way for the future commercialization and practical applications.

Other than the well-known sulfurization of molybdate compound to synthesize molybdenum disulfide (MoS ) layers, the dynamic process in the whole crystalline growth from nuclei to triangular domains has been rarely experimentally explored. Here, a competing sulfur-capture principle jointly with strict epitaxial mechanism is first proposed for the initial topography evolution and the final intrinsic highly oriented growth of triangular MoS domains with Mo or S terminations on the graphene (Gr) template. Additionally, potential distributions on MoS domains and bare Gr are presented to be different due to the charge transfer within heterostructures. The findings offer the mechanism of templated growth of 2D transition metal dichalcogenides, and provide general principles in syntheses of vertical 2D heterostructures that can be applied to electronics.

Layer-by-layer deposited anticoagulant multilayer films were prepared on ammonia plasma treated poly (vinyl chloride) (PVC). Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and contact angle results revealed the presence of -NH2 on the ammonia plasma treated PVC surfaces and the layer-by-layer self-assembly process. The stability of multilayer film was studied with the radio labeled method. The remainder bovine serum albumin (BSA) in cross-linked 5(heparin/BSA) multilayer films dipped in phosphate buffered saline (PBS, pH 7.4) was more than 90% in 40 days. The static platelet adhesion result indicated the anticoagulant multilayer films deposited on the plasma treated PVC reduced platelet adhesion drastically and no thrombus forming. The plasma recalcification time revealed that the multilayer modified surfaces greatly prolonged the plasma recalcification time. Such an easy processing and shape-independent method may have good potential for surface modification of cardiovascular devices.

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