Ultrathin polymer membrane for improved hole extraction and ion blocking in perovskite solar cells.

Highly efficient perovskite solar cells (PSCs) in the n-i-p structure have demonstrated limited operational lifetimes, primarily due to the layer-to-layer ion diffusion in the perovskite/doped hole-transport layer (HTL) heterojunction, leading to conductivity drop in HTL and component loss in perovskite. Herein, we introduce an ultrathin (~7 nm) p-type polymeric interlayer (D18) with excellent ion-blocking ability between perovskite and HTL to address these issues. The ultrathin D18 interlayer effectively inhibits the layer-to-layer diffusion of lithium, methylammonium, formamidium, and iodide ions.

Durable all inorganic perovskite tandem photovoltaics.

All-inorganic perovskites prepared by substituting the organic cations (e.g. methylammonium (MA) and formamidinium (FA)) with inorganic cations (e.

Molecular Design of Hole Transport Materials to Immobilize Ion Motion for Photostable Perovskite Solar Cells.

Poor operational stability is a crucial factor limiting the further application of perovskite solar cells (PSCs). Organic semiconductor layers can be a powerful means for reinforcing interfaces and inhibiting ion migration. Herein, two hole-transporting molecules, pDPA-SFX and mDPA-SFX, are synthesized with tuned substituent connection sites.

Na/Mo co-doped PbTiO for photocatalytic water oxidation and Z-scheme overall water splitting under visible light.

Herein, we demonstrate a sodium/molybdenum (Na/Mo) co-doped ferroelectric PbTiO for efficient photocatalysis under visible light. Doped with a high concentration of Mo, quasi-continuous new energy levels are successfully introduced below the conduction band minimum of PbTiO, giving rise to a band-to-band redshift of the absorption edge. The valence state difference of Mo and Ti in the doped PbTiO is compensated by the Na dopant, thus effectively suppressing the formation of the recombination centres caused by Mo.

Effective nitrogen doping of TiO polymorphs at mild temperatures for visible-light-responsive hydrogen evolution.

Herein, a mild-temperature nitrogen doping route with the urea-derived gaseous species as the active doping agent is proposed to realize visible-light-responsive photocatalytic hydrogen evolution both for the anatase and rutile TiO. DFT simulations reveal that the cyanic acid (HOCN), derived from the decomposition of urea, plays a curial role in the effective doping of nitrogen in TiO at mild temperatures. Photocatalytic performance demonstrates that both the anatase and rutile TiO doped at mild temperatures exhibit the highest hydrogen evolution rates, although the ones prepared at high temperatures possess higher absorbance in the visible range.

Gradient tungsten-doped BiTiNbO ferroelectric photocatalysts with additional built-in electric field for efficient overall water splitting.

BiTiNbO, a layered ferroelectric photocatalyst, exhibits great potential for overall water splitting through efficient intralayer separation of photogenerated carriers motivated by a depolarization field along the in-plane a-axis. However, the poor interlayer transport of carriers along the out-of-plane c-axis, caused by the significant potential barrier between layers, leads to a high probability of carrier recombination and consequently results in low photocatalytic activity. Here, we have developed an efficient photocatalyst consisting of BiTiNbO nanosheets with a gradient tungsten (W) doping along the c-axis.

Ion-Diffusion Management Enables All-Interface Defect Passivation of Perovskite Solar Cells.

Perovskite solar cells (PSCs) have demonstrated over 25% power conversion efficiency (PCE) via efficient surface passivation. Unfortunately, state-of-the-art perovskite post-treatment strategies can solely heal the top interface defects. Herein, an ion-diffusion management strategy is proposed to concurrently modulate the top interfaces, buried interfaces, and bulk interfaces (i.

Reexamining the Post-Treatment Effects on Perovskite Solar Cells: Passivation and Chloride Redistribution.

Post-treatment is an essential passivation step for the state-of-the-art perovskite solar cells (PSCs) but the additional role is not yet exploited. In this work, perovskite film is fabricated under ambient air with wide humidity window and identify that chloride redistribution induced by post-treatment plays an important role in high performance. The chlorine/iodine ratio on the perovskite surface increases from 0.

In Situ Passivation on Rear Perovskite Interface for Efficient and Stable Perovskite Solar Cells.

Despite the rocketing rise in power conversion efficiencies (PCEs), the performance of perovskite solar cells (PSCs) is still limited by the carrier transfer loss at the interface between perovskite (PVSK) absorbers and charge transporting layers. Here, we propose a novel in situ passivation strategy by using [6,6]-phenyl-C-butyric acid methyl ester (PCBM) to improve the charge dynamics at the rear PVSK/CTL interface in the n-i-p structure device. A pre-deposited PCBM-doped PbI layer is redissolved during PVSK deposition in our routine, establishing a bottom-up PCBM gradient that is facile for charge extraction.

Tailoring Nanoporous Structures in BiTe Thin Films for Improved Thermoelectric Performance.

Thin-film thermoelectrics (TEs) with unique advantages have triggered great interest in thermal management and energy harvesting technology for ambient temperature microscale systems. Although they have exhibited a good prospect, their unsatisfactory performances still seriously hamper their widespread application. Tailoring the porous structure has been demonstrated to be a facile strategy to significantly reduce thermal conductivity and enhance the figure of merit () of bulk TE materials; however, it is challenging for thin-film TEs.

Material and Interface Engineering for High-Performance Perovskite Solar Cells: A Personal Journey and Perspective.

Hybrid organic-inorganic perovskite solar cells (PSCs) have become a shining star in the photovoltaic field due to their spectacular increase in power conversion efficiency (PCE) from 3.8 % to over 23 % in just few years, opening up the potential in addressing the important future energy and environment issues. The excellent photovoltaic performance can be attributed to the unique properties of the organometal halide perovskite materials, including high absorption coefficient, tunable bandgap, high defect tolerance, and excellent charge transport characteristics.

Flexible layer-structured BiTe thermoelectric on a carbon nanotube scaffold.

Inorganic chalcogenides are traditional high-performance thermoelectric materials. However, they suffer from intrinsic brittleness and it is very difficult to obtain materials with both high thermoelectric ability and good flexibility. Here, we report a flexible thermoelectric material comprising highly ordered BiTe nanocrystals anchored on a single-walled carbon nanotube (SWCNT) network, where a crystallographic relationship exists between the BiTe <[Formula: see text]> orientation and SWCNT bundle axis.

Cellulose Fiber-Based Hierarchical Porous Bismuth Telluride for High-Performance Flexible and Tailorable Thermoelectrics.

Porous modification is a general approach to endowing the rigid inorganic thermoelectric (TE) materials with considerable flexibility, however, by which the TE performances are severely sacrificed. Thus, there remains an ongoing struggle against the trade-off between TE properties and flexibility. Herein, we develop a novel strategy to combine BiTe thick film with ubiquitous cellulose fibers (CFs) via an unbalanced magnetron sputtering technique.

Dislocation-induced nanoparticle decoration on a GaN nanowire.

GaN nanowires with homoepitaxial decorated GaN nanoparticles on their surface along the radial direction have been synthesized by means of a chemical vapor deposition method. The growth of GaN nanowires is catalyzed by Au particles via the vapor-liquid-solid (VLS) mechanism. Screw dislocations are generated along the radial direction of the nanowires under slight Zn doping.

Mesoporous TiO2 single crystals: facile shape-, size-, and phase-controlled growth and efficient photocatalytic performance.

In this work, we have succeeded in preparing rutile and anatase TiO2 mesoporous single crystals with diverse morphologies in a controllable fashion by a simple silica-templated hydrothermal method. A simple in-template crystal growth process was put forward, which involved heterogeneous crystal nucleation and oriented growth within the template, a sheer spectator, and an excluded volume, i.e.

A quasi-quantum well sensitized solar cell with accelerated charge separation and collection.

Semiconductor-sensitized solar cell (SSSC) represents a new generation of device aiming to achieve easy fabrication and cost-effective performance. However, the power of the semiconductor sensitizers has not been fully demonstrated in SSSC, making it actually overshadowed by dye-sensitized solar cell (DSSC). At least part of the problem is related to the inefficient charge separation and severe recombination with the current technologies, which calls on rethinking about how to better engineer the semiconductor sensitizer structure in order to enhance the power conversion efficiency (PCE).

Building high-efficiency CdS/CdSe-sensitized solar cells with a hierarchically branched double-layer architecture.

We report a double-layer architecture for a photoanode of quantum-dot-sensitized solar cells (QDSSCs), which consists of a ZnO nanorod array (NR) underlayer and a ZnO nanotetrapod (TP) top layer. Such double-layer and branching strategies have significantly increased the power conversion efficiency (PCE) to as high as 5.24%, nearly reaching the record PCE of QDSSCs based on TiO2.

All-solid-state hybrid solar cells based on a new organometal halide perovskite sensitizer and one-dimensional TiO2 nanowire arrays.

A novel organometal halide perovskite (CH3NH3PbI2Br) is synthesized and used as a visible light absorber to sensitize one-dimensional (1D) TiO2 nanowire arrays (NWAs) for all-solid-state hybrid solar cells. It achieved a power conversion efficiency (PCE) of 4.87% and an open circuit voltage (Voc) of 0.

Density-controlled electrodeposition growth of zinc oxide nanorod arrays.

Density-controlled zinc oxide (ZnO) nanorod arrays were synthesized on indium tin oxide (ITO) substrates via a potentiostatic electrodeposition method under different conditions. The effects of preparing conditions on the density of nanorods were systematically investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). It is demonstrated that the density and diameter of ZnO nanorods can be effectively controlled by varying the electrodeposition parameters, such as electrodeposition potential, concentration of Zn2+ precursor and growth temperature.

Electrodeposition of hierarchical ZnO nanorod-nanosheet structures and their applications in dye-sensitized solar cells.

We present a two-step electrochemical deposition process to synthesize hierarchical zinc oxide (ZnO) nanorod-nanosheet structures on indium tin oxide (ITO) substrate, which involves electrodeposition of ZnO nanosheet arrays on the conductive glass substrate, followed by electrochemical growth of secondary ZnO nanorods on the backbone of the primary ZnO nanosheets. The formation mechanism of the hierarchical nanostructure is discussed. It is demonstrated that annealing treatment of the primary nanosheets synthesized by the first-step deposition process plays a key role in synthesizing the hierarchical nanostructure.