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Phthalide and 1-Iodooctadecane Synergistic Optimization for Highly Efficient and Stable Perovskite Solar Cells
No full textThe carrier non-radiative recombination and instability of device caused by the inherent defects are main factors limiting development of perovskite solar cells (PSCs). During the fabrication process of a PSC device, perovskite films often produce Pb-0 and I-0 defects. This paper reports a strategy for synergistic optimization of perovskite films by defects passivation and surface modification. The doping of phthalide (PT) in the Pb-rich (CH(NH2)(2))(1-x)(CH3NH3)(x)PbI3 film can passivate lead cation defects, and the modification of 1-iodooctadecane (1-IO) can reduce halogen anion defects and improve stability of PSCs owing to its hydrophobicity. The PT and 1-IO optimized device achieves a power conversion efficiency (PCE) of 22.27%. The optimized PSCs remain 93.2% of the initial PCE when placed in air environment (relative humidity of 10%, 25 degrees C) more than 70 days. The PT and 1-IO synergistic optimization provides a novel strategy for improving the performance and stability of PSCs
Research progress of two-dimensional covalent bond substructure Zintl phase thermoelectric materials
No full textThermoelectric materials can realize the direct conversion between thermal energy and electrical energy, and thus having important applications in semiconductor refrigeration and heat recovery. Zintl phase is composed of highly electronegative cations and anions, which accords with the concept of phonon glass, electron crystal (PGEC). Thermoelectric properties of Zintl phase have attracted extensive interest, among which the two-dimensional (2D) covalent bond structure featured Zintl phases have received more attention for their outstanding electrical properties. In this review, Zintl phase materials with two-dimensional covalent bond substructures are reviewed, including 1-2-2 type, 9-4+x-9-type, 2-1-2 type and 1-1-1 type Zintl phase. The 1-2-2-type Zintl phase is currently the most widely studied and best-performing Zintl material. It is worth mentioning that the maximum ZT value for the Mg3Sb2-based n-type Zintl material with the CaAl2Si2 structure has been reported to reach 1.85, and the average ZT value near room temperature area also reaches 1.4. The 9-4+x-9-type Zintl material with a mass of atoms in unit cell contributes to lower thermal conductivity thus relatively high ZT value. The 2-1-2-type Zintl material has extremely low thermal conductivity due to the intrinsic vacancies, which has been developing in recent years. The 1-1-1-type Zintl material with the same ZrBeSi structure as the 2-1-2-type Zintl material, shows better electrical transport performance. In sum, this review summarizes the recent progress and optimization methods of those typical Zintl phases above. Meanwhile, the future optimization and development of Zintl phase with two-dimensional covalent bond substructures are also prospected
A Self-Healing and Ionic Liquid Affiliative Polyurethane toward a Piezo 2 Protein Inspired Ionic Skin
No full textIonic skin (I-Skin) has the advantage of feasible compatibility with biological systems. Nevertheless, developing a stable and durable ionic skin is challenging. Here, an ionic polyurethane (i-PU) is synthesized, which is capable of self-healing and able to lock the ionic liquids (ILs). In detail, an ionic chain extender containing an ammonium cationic group is synthesized, followed by the polymerization to obtain the target i-PU. Through electrostatic interaction and chain diffusion, the i-PU can be fully self-healed at room temperature within 400 min. Afterward, low contact angle (37 degrees) of the i-PU against IL and the density functional theory (DFT) calculation prove their good compatibility and strong interaction, originating from the electrostatic interaction. The Raman intensity map shows the reversible process of the enrichment and restoration of ionic concentration on the i-PU/IL surface when external pressure is applied or released, proving stable binding of ions by ionic polymer chains. Lastly, the self-healing I-Skin based on the i-PU/IL is fabricated with a wide range of pressures (0-120 kPa), fast response time (32 ms), excellent antifatigue property (2% attenuation after 1000 cycles), and remarkable sensitivity (52.4 kPa(-1))
Synthesis and characterization of Bi-doped antimony sulphide thin films for solar absorption applications
No full textProducing stable semiconducting thin films with low band gap energy by a viable technique is challenging for solar energy harvesting. Herein, Bi-doped Sb2S3 thin films have been deposited on glass substrates by chemical bath deposition (CBD) technique followed by annealing at 400 degrees C. X-ray diffraction (XRD) patterns confirmed the orthorhombic phase of Sb2S3 and successful incorporation of Bi+3 in the host lattice. Raman spectroscopy revealed the characteristic vibrational modes of Sb2S3. Surface of films became smoother and compact with increasing Bi contents. Samples showed wide absorption range in the visible region. Band gap energy (Eg) values were estimated using Tauc's relation and a blue shift in the absorption edge was observed with addition of Bi, thus Eg increased from 1.58 to 1.71 eV. Higher values of absorption coefficient and absorption edge in the visible region suggest that the prepared Sb2S3 thin films can be a right choice of an absorber layer
Dual-functional carbon-doped polysilicon films for passivating contact solar cells: regulating physical contacts while promoting photoelectrical properties
No full textPassivating contact crystalline silicon solar cells are among the most promising industrially feasible photovoltaic (PV) technologies and require excellent physical contacts to handle device performance. Here, we report a versatile polysilicon (poly-Si) film intentionally doped with carbon (C) to suppress blistering and improve physical contacts. Our investigations of blistering mechanisms reveal that the reduced crystallization fraction of poly-Si in conjunction with the suppressed level of hydrogen release should primarily be responsible for the blistering-free appearance of the C-doped poly-Si films. Moreover, additional advantages of high-quality passivation with a high implied open-circuit voltage (iV(oc)) exceeding 750 mV and an excellent optical response in the infrared band with a net current-density gain of 0.31 mA cm(-2) are endowed to the C-doped poly-Si films. Consequently, the proof-of-concept devices featuring C-doping show a champion efficiency of 24.27%, which is 1.18% higher than that of the C-free counterparts (23.09%). Also, we present a certified efficiency of 23.82%, suggesting that the C-doped poly-Si has the potential to achieve high-efficiency c-Si solar cells
Efficient Fenton-like treatment of high-concentration chlorophenol wastewater catalysed by Cu-Doped SBA-15 mesoporous silica
No full textEffective treatment for industrial wastewater that contains high concentration of chlorophenols is urgent and indispensable for environmental governance and human health due to their nonbiodegradable, carcinogenic and cytotoxic properties. Four kinds of Cu-containing mesoporous silica materials were utilized to catalyse Fentonlike treatment of high-concentration chlorophenols wastewater (1.0 g L-1). All of chlorophenols in various water matrices could be oxidatively decomposed in 35 min with the catalysis of Cu-doped SBA-15. Cu-doped SBA-15 with a Cu/Si molar ratio of 0.133 had the best catalytic activity in the oxidative degradation of 4-chlorophenol with an apparent reaction rate constant of 0.170 min(-1) which was 1.3-3.6 times higher than those with other Cu-containing catalysts. After 300 min reaction, total organic carbon content of 4-chlorophenol solution declined continuously to 23.8% with an advisable utilization efficiency of H2O2 of 26.5%-68.4%. Electron spin resonance tests and quenching experiments demonstrated that Cu-doped SBA-15 had a selective catalytic activity in the decomposition of H2O2 into hydroxyl radicals which dominated the degradation of chlorophenols in wastewater. The redox of Cu(II)/Cu(I) in Cu-doped SBA-15 occurred efficiently, which could be attributed to chemical adsorption and electron transformation of organic molecular fragments onto Lewis acidic sites formed by the incorporation of Cu2+ ions in SBA-15. The biological toxicity of the treated 4-CP wastewater declined significantly in comparison with that of the original wastewater. Our work provided an effective way of the heterogeneous treatment of high-concentration chlorophenol wastewater
Improvement of thermoelectric properties of SnTe by Mn-Bi codoping
No full textSnTe is an attracted lead-free thermoelectric material, but the thermoelectric performance is severely limited by the high hole concentration, undesirable valence band structure and high thermal conductivity. In this work, we study the multiple effects of Mn-Bi codoping in SnTe to synergistically improve the overall power factor and ZT values. It is found that the Mn-Bi codoping effectively reduces the hole concentration to an optimal range. As expected, Mn and Bi doping obviously decreases the energy separation between the two valence band maxima, enabling pronounced band convergence and improved Seebeck coefficient. Moreover, Mn-Bi codoping introduces various phonon scattering centers to scatter a wide spectrum of phonons for a suppressed lattice thermal conductivity of 0.67 W m(-1) K-1 at 850 K. The synergy of these effects yields a peak ZT of 1.3 at 850 K and an average ZT of 0.68 (300-850 K) in Sn0.90Mn0.07Bi0.03Te, suggesting SnTe-based material a promising candidate for medium-temperature thermoelectric applications
TADF Molecule as an Interfacial Layer with Cascade Energy Alignment Enabling High Open-Circuit Voltage for 3D/2D Perovskite Solar Cells
No full textThe minimum interface recombination and maximum carrier extraction of perovskite solar cells (PSCs) are important for achieving a better power conversion efficiency (PCE). According to the recent investigations, 3D/2D hybrid perovskite systems have been recognized as an effective approach to improve the efficiency and stability of PSCs. However, a large highest occupied molecular orbital energy level gap between a 2D perovskite and the hole transport layer (HTL) spiro-OMeTAD would cause energy losses at the interface, which limit open-circuit voltage (V-oc) and thus PCE of the PSCs. In this work, we utilized a thermally activated delayed fluorescence molecule M1 stacked on the 3D/2D hybrid perovskite films to engineer the 3D/2D perovskite/HTL interface. The ultrathin interfacial layer of M1 forms a cascade energy alignment between 3D/2D perovskites and a HTL, as a means to circumvent energy losses, which consequently improves the efficiency of PSCs from 19.56 to 21.48% with an outstanding increase of V-oc from 1.18 to 1.23 V. The charge separation and carrier recombination in PSCs were analyzed by photoluminescence and impedance characterization, from which, we deduce that a suitable energy level structure can reduce interface charge recombination and promote a minimal open-circuit voltage (V-oc) loss, which facilitate the improvement of PSC performances
Hydrolytically stable foamed HKUST-1@CMC composites realize high-efficient separation of U(VI)
No full textHKUST-1@CMC (HK@CMC) composites that show good acid and alkali resistance and radiation resistance were successfully synthesized by introducing carboxymethyl cellulose (CMC) onto the surface of HKUST-1 using a foaming strategy. For the first time, the composites were explored as efficient adsorbents for U(VI) trapping from aqueous solution, with encouraging results of large adsorption capacity, fast adsorption kinetics, and desirable selectivity toward U(VI) over a series of competing ions. More importantly, a hybrid derivative film was successfully prepared for the dynamic adsorption of U(VI). The results show that similar to 90% U(VI) can be removed when 45 mg L-1 U(VI) was passed through the film one time, and the removal percentage is still more than 80% even after four adsorption-desorption cycles, ranking one of themost practical U(VI) scavengers. This work offers new clues for application of the Metal-organic-frame work-based materials in the separation of radionuclides from wastewater
Coupling between antiferromagnetic and spin-glass orders in the quasi-one-dimensional iron telluride TaFe1+xTe3(x=0.25)
No full textUnderstanding the interplay among different magnetic exchange interactions and its physical consequences, especially in the presence of itinerant electrons and disorder, remains one of the central themes in condensed matter physics. In this vein, the coupling between antiferromagnetic and spin-glass orders may lead to large exchange bias, a property with potential broad technological applications. In this paper, we report the coexistence of antiferromagnetic order and spin-glass behaviors in the quasi-one-dimensional iron telluride TaFe1+xTe3 (x = 0.25). Its antiferromagnetism is believed to arise from the antiferromagnetic interchain coupling between the ferromagnetically aligned FeTe chains along the b axis, while the spin-glassy state stems from the disordered Fe interstitials. This dichotomic role of chain and interstitial sublattices is responsible for the large exchange bias observed at low temperatures, with the interstitial Fe acting as the uncompensated moment and its neighboring Fe chain providing the source for its pinning. This iron-based telluride may thereby represent a paradigm to study the large family of transition metal chalcogenides whose magnetic order or even dimensionality can be tuned to a large extent, forming a fertile playground to manipulate or switch the spin degrees of freedom thereof