Search

Due to the ongoing depletion of fossil energy, alternative energy-sources and their respective conversion technologies have become very essential. An inexhaustible and clean energy form, which is already widely used, is solar energy. However, despite much progress in recent decades, due to the limitations of materials and manufacturing technology, the ability of solar cells to convert light into electrical energy is still not very high. Enhancing light absorption and reducing electric loss are the keys to improving the overall conversion efficiency of solar cells and reducing raw material costs. The former can be achieved by using micro/nanostructures and other surface features, while the latter can be realized by surface passivation. Researchers have developed different silicon-surface texturing methods to fabricate random or periodic micro/nanostructures on the surface of silicon wafers. Thanks to the special and efficient light-trapping effects of silicon micro/nanostructures, both full angle and wideband light absorption can be achieved. Different passivation methods and materials have also been widely studied, which helps to improve the surface recombination of photogenerated carriers caused by light trapping structure and significantly enhance the power conversion efficiency of Si solar cells. In this work, theoretical studies of enhanced light-trapping in micro/nanostructures are introduced. In addition, several advanced methods for preparing micro/nanostructures on the surface of monocrystalline silicon are discussed. These can be classified as top-down and bottom-up approaches. Furthermore, passivation methods for micro/nanostructures on the surface of monocrystalline silicon solar cells are reviewed, including chemical passivation and field-effect passivation. Finally, advantages and disadvantages of the micro/nanostructure preparation technologies, and light-trapping effects of the micro/nanostructures, which were fabricated using these manufacturing technologies were summarized. Moreover, the effects of different passivation technologies on the optical properties and electrical properties of these micro/nanostructures are studied. An outlook of expected and emerging research directions for monocrystalline silicon solar cells concludes this study.

Due to their low cost, tunable band gap and excellent thermostability, all-inorganic halide perovskites CsPbX

With the increasing demand for near-infrared (NIR) detection in the fields of automation, military industry, communications and medical health, how to develop novel high quality and low cost NIR photodetectors has become a research hotspot in recent years. In order to solve the problems such as expensive raw materials, complex production equipment and difficulty in integration of traditional III–V semiconductors, PbS quantum dots (QDs) have become the most promising emerging nanomaterials for commercial NIR detection due to their excellent light absorption performance, low cost, simple deposition process and tunable band gap. This review summarizes the development strategies of PbS QD-based photodetectors over the past, focusing on the performance of devices with different structures and the feasibility of commercialization. In order to meet the needs of modern industry for NIR detection and realize commercialization, PbS QD-based photodetectors need to make breakthroughs in detection performance, device stability, device integration and large-scale preparation. These contents are discussed in detail in this paper. By comparing different strategies, the deficiencies of PbS QD-based photodetectors are proposed, and it is hoped that it can provide a reference for the further development of PbS QD-based photodetectors.

The cost-effective processability and high stability of carbon-based perovskite solar cells (C-PSCs) have shown great potential to positively devote to the development of large-scale production processes. However, there are certain critical issues such as inferior performance and poor interface contact between perovskites and carbon electrodes, which have to be resolved first. The review shows that three main carbon materials, namely, carbon black, graphenes and carbon nanotubes display high photoelectric conversion efficiencies when being mixedly used as rigid electrodes and show excellent robustness in mechanical deformation as flexible carbon electrodes in carbon-based perovskite solar cells. Moreover, the specific development of and the comparison among three primary types of C-PSCs, namely, meso C-PSCs, embedment C-PSCs and paintable PSCs are emphasized. Furthermore, this work discusses the latest progress of C-PSC interface engineering from four aspects, namely, energy alignment, hysteresis effect, interface passivation and built-in electric field, and the differences among them are explained. Finally, further challenges and perspectives of C-PSCs are outlined. This work will be a profound influence and guidance on the significance of C-PSCs in commercialization.

Recently, perovskite nanocrystals (NCs) have become highly promising materials due to their unique optical and electrical properties such as high absorption coefficient, high photoluminescence quantum yield, and long exciton diffusion length. It is well known that the band gap of perovskite nanocrystals can be tuned by composition engineering, ranging from the ultraviolet to near-infrared regions. Moreover, thanks to the solution-processing feature, perovskite NCs have become much popular for various photodetectors. Hence, in this review, we carefully introduce the developmental progress of perovskite NCs and photodetectors, including the aspects of synthetic procedures, device architectures, working mechanism, and optimization procedures. Besides, great achievements and challenges, in terms of the high photosensitivity and detectivity, are also discussed for perovskite NC-based photodetectors. Finally, the application perspective of next generation photodetectors is prospected, which provides a reference for the related study.

Developing low-cost and highly efficient hydrogen evolution reaction (HER) electrocatalysts is an important research area for large-scale hydrogen production. Herein, we report a new nanohybrid con...

The photoinduced phase segregation (PIPS) of mixed-halide perovskites (MHPs), due to halogen migration, has reaped considerable attention for its retroaction on film photostability and photovoltaic...

Nickel oxide (NiOx) film is employed to replace PEDOT:PSS as the hole transport layer for the inverted perovskite solar cells (PSCs) with Zinc Oxide as electron transport layer, and we focus on the...

The tunable bandgap of mixed-halide perovskites (MHPs) makes them suitable for high-performance single-junction photovoltaics (PVs), as well as wide-bandgap components for multi-junction (tandem) structures. However, the composition engineering of halide ions, an effective procedure to adjust the bandgap of MHPs for PVs, result in photoinstability in MHPs due to the photo-induced anion phase segregation (PIAPS) effect. Specifically, MHP materials experience an inevitable phase transition from homogeneous alloys to conjugated lower/higher-bandgap phases, that is, iodide/bromide (I/Br)-rich domains, upon exposure to light. Reasonably, the sub-bandgap trapping states can lead to film inhomogeneity and performance deterioration in PVs. Meanwhile, it has been widely proven that the PIAPS phenomenon, even though it is reversible, may limit the commercial integration of MHPs in tandem applications because of their unstable output. Hence, in this review, initially, we study, analyze, and explore the “fashionable” PIAPS phenomenon systematically. Then, the feasible protocols to stabilize MHP materials, especially based on their correlation with the inherent mechanism of the PIAPS phenomenon, are adequately exhibited to help researchers develop more suitable procedures for its suppression. Finally, we provide some potential research points to study the PIAPS phenomenon and stabilize MHPs for their future commercial applications.

The reversible activation process, which involves electron transfer from adjacent redox mediators to cofactors, the reversible chemical state change of cofactors, and the functional/structural change of redox mediators, is one of the most significant features of biological enzymes, and has inspired the design of homogeneous catalysts. However, for heterogeneous catalysts, such enzyme-like characteristics have been only observed in very few transition metal–organic frameworks (MOFs) and single copper atom incorporated TiO2 catalysts during dynamic photocatalytic processes, and have never been seen in industrially important visible light-driven narrow-band gap semiconductor catalysts. Herein, we first report on the design and synthesis of highly active CdS/Co–N redox catalysts through the pyrolysis of trithiocyanuric acid cadmium-cobalt (CdCoTMT) coordination polymers as single-source precursors, which exhibit a reversible photoactivation process. This unique design and synthetic strategy provide a platform that facilitates atomic-level anchoring control of cofactor transition metal atoms (Co2+ and Ni2+), reversible modulation of the macroscopic optoelectronic properties of CdS and enhancement of photocatalytic hydrogen evolution, promoting the practical application of conventional heterogeneous catalysts.

The development of non-noble metal electrocatalysts with high performance for the oxygen evolution reaction (OER) is highly desirable but still faces many challenges. Herein, we report a facile and controllable strategy to fabricate N-doped titanium carbide flakes (Ti3C1.8N0.2 and Ti3C1.6N0.4) using an in situ nitrogen solid solution, followed by an etching process. The introduction of nitrogen is beneficial to the Ti3C1.6N0.4 flakes for more exposed active sites, accelerated charge transfer upon an electrochemical reaction, and improved wettability for more accessible sites. As a result, the as-obtained Ti3C1.6N0.4 catalyst exhibits enhanced electrocatalytic properties for OER, which include a small ηonset of 245.8 mV, low Tafel slope of 216.4 mV dec−1, and relatively good catalytic stability. The present work not only deepens the understanding of in situ N-doped MXene electrocatalysts, but also provides a guideline for the preparation of other N-doped MXene-based hybrid materials for other renewable energy applications.

To acquire better nitrogen doping results of titanium carbides (MXenes), methanol (MT) solvent with high fluidity and smaller micromolecule size is selected to assist the introduction of nitrogen o...

The anti-fouling copper-zinc-tin-selenide (CZTSe) nanocarambolas were synthesized and deposited on a hydrophilic filter membrane, as the full solar spectrum absorber and nanoporous vapor generator, for efficient and stable solar-driven interfacial water evaporation. The CZTSe nanocarambolas assembled membrane based self-floatable device with excellent light-to-heat conversion, abundant nanochannels, anti-fouling property, timely water supply and low heat loss achieved a remarkable solar evaporation rate of 1.528 kg/m2 h and a solar-to-vapor conversion efficiency up to 86.4% under one Sun, and stable solar desalination over 30 days without decay. This assembled membrane showed an excellent salt-rejection ability and a potential application of long-term efficient, stable and safe solar water purification of seawater and wastewater, and practical freshwater production under natural conditions.

Designing a hybrid architecture of electroactive species on the modified graphene sheets is one of the most promising tactics for high-performance supercapacitors. Herein, multiphase nickel sulfides nanoparticles (Ni3S2-NiS, abbreviated as Ni-S-1) with abundant edge sites were synthesized by pyrolysis of three-dimensional porous Ni-C3N3S3 complexes, and then the N-doped graphene (NG)/Ni-S-1 hybrid was obtained by an introduction of graphene oxide. The NG/Ni-S-1 hybrid shows the electroactive species-on-sheet architectures and the heteroatom nitrogen doping into graphene. The unique structural composition of the NG/Ni-S-1 hybrid can accelerate the permeation and shorten the diffusion length of electrolyte ions, to perform favorable electrochemical charge storage kinetics. Remarkably, compared with Ni-S-1 electrode, the NG/Ni-S-1 hybrid electrode delivers an improved specific capacity of 732.1 C g−1 at 1 A g−1 and an excellent rate capability, which are attributed to more accessible surfaces and enhanced electron-transport capacity due to the integration of NG matrix. Furthermore, a hybrid supercapacitor assembled using the NG/Ni-S-1 hybrid as positive electrode and activated carbon (AC) as negative electrode demonstrates a high energy density of 40.2 Wh kg−1, high power density of 7.4 kW kg−1, and relatively good electrochemical stability. The facile strategy may offer a new opportunity for fabrication of transition metal sulfides-based hybrids for high-performance supercapacitors.

Devices with printable carbon electrodes are promising directions for the commercialization of perovskite solar cells. Most of perovskite solar cells employ mesoporous device structures when using printable carbon as the counter electrodes. Here, we carry a comparative study of planar and mesoporous perovskite solar cells with carbon electrodes. The device efficiency is significantly reduced from 11.37% to 5.27% when the mesoporous TiO2 film is removed from the device structure. Compared with the planar device, smaller carrier transport resistance and bigger carrier recombination resistance are demonstrated for the mesoporous device. Results suggest that the presence of mesoporous TiO2 enables an efficient electron extraction from the perovskite absorber, which remits the serious carrier recombination in the hole transport layer free device due to the hole accumulation. Therefore, the electron extraction efficiency is crucial in these hole transport layer free devices with carbon electrodes. This study helps to develop further optimization of low temperature carbon-based perovskite solar cells for higher reproducibility and higher device performance.

Oxygen evolution reaction (OER) is an important kinetic process in many important renewable energy applications, while high-efficiency electrocatalysts, especially efficient non-precious metal catalysts, are very essential to overcome substantial overpotential and sluggish kinetics of OER. Here, three-dimensional (3D) Ti3C2 based conductive network structure was firstly constructed by an absorption of 2D few-layer Ti3C2 flakes (MXene) onto 3D nickel foam (NF) network, and then ultra-small sulfur-incorporated nickel ferrite nanosheets (S-NiFe2O4) were grown on the 3D Ti3C2 based conductive network structure (abbreviated as S-NiFe2O4@Ti3C2@NF) by combining a facile thiourea-assisted electrodeposition process with a low-temperature calcination process. Results indicate that the as-fabricated S-NiFe2O4@Ti3C2@NF hybrid electrode exhibits a superior OER activity, which includes only 1.50 V vs. RHE to afford a current density of 20 mA cm−2, a Tafel slope of 46.8 mV dec−1 and excellent catalytic stability in 1 M KOH. Excellent OER performances are attributed to the favorable 3D hierarchical network structure and relatively fast electron transport provided by the few-layer Ti3C2 flakes matrix, good catalytic activity and abundant catalytic active sites from the ultra-small S-NiFe2O4 nanosheets, synergistically. This work could open a feasible way for achieving a new type of 3D MXenes based hierarchical network structure for renewable energy applications.

Trithiocyanuric acid trisodium salt hydrate (Na3TMT) has been proved an excellent heavy metal chelating agent and widely applied for heavy metal ions elimination in industrial wastewater. In this work, the chelating products of Bismuth(III) ion with this effective agent were prepared by solid state and liquid phase reactions, and proved as a new kind of n-type semiconductor. For full utilization of resource, the green and low-cost massive Bismuth chelate with good crystallinity, distinctive morphology, appropriate band structure and high stability was applied for photoelectrochemical application and photocatalytic organic pollutants degradation upon visible light. Results indicated that OH radicals were the main reactive specie in the photodegradation process. The combination of heavy metals and organic contaminants removal was achieved by a waste-to-wealth route.

Tin oxide (SnO2) has been confirmed as a vital electron transport material for efficient planar perovskite solar cells (PSCs) owing to its outstanding electrical and optical properties. Defectively, the SnO2 electron transport layer (ETL) by spin coating still remains great challenges for repeatable planar heterojunction PSCs fabrication for its limited scale and incompetent uniformity. Herein, the vacuum thermal-evaporation procedure is employed to achieve this intent by the dense and uniform SnO2 layer, which can largely improve the material utilization for cost reduction and act as a potential for the prospective industrial large-scale fabrication. Besides, a post-annealing treatment of evaporated SnO2 is proved obbligato to achieve an ideal crystallinity improvement. Furthermore, to remove the antisolvent method for perovskite, methyl ammonium acetate (MAAc) worked as an additive into the perovskite precursor for a pure MAPbI3 film to achieve the poisonous antisolvent free. Noticeable, the formation of an unstable MAPbI3-xAcx intermediate certainly has a great impact on the resulting perovskite, in which the particular surface-morphology was dominated by the MAAc volatilization rate. The obtained morphology with fluctuant pits and ridges, like a 3D-structure, contributes to more light absorption and contact area at perovskite/charge transport material interface, leading to higher photocurrent, more efficient charge extraction and better device performance. As a result, an optimal cell device can remain 86% of its initial photovoltaic performance (PCE: 16.79%) after a 50-d storage in air.

Low temperature derived carbon electrodes are employed to fabricate low cost hole transport layer free perovskite solar cells, in which perovskite films annealed in glovebox and ambient air are used as the absorbers, respectively. Results suggest that the air annealed sample has bigger crystal grains and higher crystallinity, and the existence of a small amount of lead iodide which passivates grain boundaries contributes to a lower trap density. As a result, a maximum power conversion efficiency (PCE) of 13.07% was obtained on the air annealed device, which is higher than those of devices annealed in glovebox (11.25%). Furthermore, the stability of unencapsulated devices stored in wet (with humidity around 90% ± 5%) air atmosphere are investigated and the results prove that our devices exhibit good stability. In addition to rigid devices, flexible perovskite solar cells are also fabricated using the same procedure. The highest PCE of 11.53% is demonstrated on the champion flexible device, and 69% of its initial PCE can be maintained even after 2000 bending cycles with a bending radius of 2 mm. Our work provides a promising and simple rout for low-cost, air-stable, high-efficiency carbon perovskite solar cells for both large area production and flexible electronic devices industry.

The photoinduced phase segregation (PIPS) of mixed-halide perovskites (MHPs), due to halogen migration, has reaped considerable attention for its retroaction on film photostability and photovoltaic output. Nevertheless, the original mechanism is still unclear. Herein, taking the representative CsPbIBr

Organometal halide perovskites (OHPs) are a kind of promising materials applied in solar cells. However, the toxicity of lead in OHPs is considered as an environmental problem. Herein, we report two lead-free two-dimensional (2D) iodide-based OHPs, namely (C6H16N2)2AgBiI8·H2O (AgBiI) and (C6H16N2)2CuBiI8·0.5H2O (CuBiI), where C6H14N2 = 1,4-cyclohexanediamine, with a double perovskite structure. These two bimetallic perovskites show the optical band gaps of 1.93 eV and 1.68 eV. In addition, these 2D perovskite materials can form smooth films through a simple one-step spin-coating approach. Photocurrent measurements under xenon lamp irradiation indicate obvious photoresponses, suggesting that these semiconducting materials have the potential for application in light harvesting.

An efficient-photoanode for the dye-sensitized solar cells (DSSCs) should have several features, such as high dye-uploading, favorable energy band-gaps and excellent capability in electronic-transport. Herein, TiO2 nanohexagon arrays (TNHAs) were fabricated by using an electrochemical anodization process. Then, TNHAs were attached onto the FTO glass for front-illuminated approach of the DSSCs. SnO2 is a promising wide band-gap material for DSSCs due to its high electron-mobility. To enhance the performance of DSSCs, SnO2 nanoparticles were offered into the TNHAs by using a one-step facile immersion approach in 0.25 M K2SnO3 solution for 30 min. The as-fabricated SnO2/TNHAs were utilized as the efficient-photoanodes for DSSCs. The SnO2 nanoparticles have a superior light harvesting capability owe to the higher upper-surface area for maximum dye-uploading and the high electron-mobility. The SnO2/TNHAs based DSSC had a PCE of 6.43%, which was 1.34 fold higher than those of pure TNHAs. Furthermore, IPCE and the amount of dye adsorption were also improved.

Considering both the features of bandgap and stability, CsPbIBr2 presents a promising potential among the inorganic perovskite photovoltaic materials. Nevertheless, the poor quality films derived from the precursor solution acutely hinders the performance improvement of cells. Herein, high-quality CsPbIBr2 perovskite films are effectively fabricated through a facile one-step spin-coating method assisted by a preheating process. During spin coating, the reserved substrate heat accelerates solvent molecule volatilization, resulting in the complete coverage and enhanced crystallinity of the CsPbIBr2 films. Upon optimizing the substrate-preheating temperature precisely, perovskite solar cells (PSCs) with a configuration of ITO/SnO2/CsPbIBr2/spiro-OMeTAD/Ag exhibit a superior power conversion efficiency (PCE) of 9.86% with a stabilized output of 8.78% and an open-circuit voltage (Voc) of 1.267 V, all of which represent the excellent properties of the pure CsPbIBr2-based cells. Moreover, this work provides a promising route for the fabrication of inorganic perovskites.

Flexible perovskite solar cells are arising researchers’ attentions due to their promising potential applications. In this letter, homogeneous and highly crystalline SnO2 nanoparticles are successfully synthesized by a solvothermal method, which are then employed to deposit high quality electron transport layers by spin coating and baking at a temperature as low as 150 °C. The prepared SnO2 layer has a homogenous and flat surface without any pinholes. The resulting flexible perovskite solar cell shows a high power conversion efficiency of 13.90%, which is mainly attributed to the good transmittance, efficient electron extraction and hole blocking ability of the SnO2 electron transport layer.

Supercapacitors (SCs), environment-friendly high-power energy storage devices, have drawn great attention due to the increasing and urgent development of renewable energies. Ti3C2Tx (MXene), a 2D high conductivity material, has been shown to be a potential electrode material for SCs, because of its outstanding chemical and physical properties. However, the surface termination of –F and –OH could block the transport of electrolyte ions and thus decrease the energy storage performances. In this regard, nitrogen related functional groups have been introduced to modify the surface characteristics of Ti3C2Tx, in order to increase the electron conduction and energy storage capacity. Experimental results have shown that the presence of moieties such as –NH2, Ti–O–N and O–Ti–N, could offer a synergistic effect on the electrochemical performance of SCs, which is mainly attributed to the intercalation-pseudocapacitance contribution according to the quantitative analysis. Furthermore, the role of O–Ti–N is more significant than that of Ti–O–N. Specifically, for the first time, we demonstrate that electrodes based on the N surface modified Ti3C2Tx film display largely enhanced electrochemical performances, with gravimetric capacitance of 415.0 F g−1 at 2 mV s−1, rate capacity of 75.9% at 200 mV s−1 and cycling stability of above 90% retention after 18 000 cycles. In addition, symmetric SCs based on the N–Ti3C2Tx-300 film could deliver a maximum volumetric energy density of 21.0 W h L−1 and an energy density of 10.2 W h L−1, at a high power density of 18.3 kW L−1.

To achieve a reproducible perovskite film with full surface coverage, Zn 2+ ions are introduced to partially replace Pb 2+ ions in this work. Results indicate that the crystallization and formation of CH 3 NH 3 Pb 1−x Zn x I 3 film with micrometer grain size could be changed by the micro-strain for lattice shrink. The bandgap and optical properties of perovskite films are improved due to trace amounts of Zn 2+ ion dopant. More importantly, the solar cell device based on the Zn-doped perovskite film shows an increment in photocurrent of 21.13 mA cm −2 and power conversion efficiency (PCE) of 16.6%. Electrochemical impedance spectroscopy (EIS) measurements reflect that the charge recombination resistance and charge accumulation capacitance of devices based on MAPb 0.98 Zn 0.02 I 3 film are lower than that of the control device. However, present results also implied that MAPb 1−x Zn x I 3 films are still necessary to be extensively developed and optimized for further enhancing the device photovoltaic performance.

Ternary Cu2SnS3 (CTS) and Cu2SnSe3 (CTSe) quantum dots were grown in-situ on reduced graphene oxide (rGO) nanosheets by a facile one-pot colloidal synthesis. Possessing abundant active sites and having the ability to harvest solar energy and to facilitate charge separation, the CTS(e)/rGO 0D/2D nanocomposites showed remarkably enhanced photocatalytic activities for degradation of rhodamine B and methyl orange aqueous solutions upon visible light irradiation. The nanocomposites of rGO supported monodispersed quantum dots were proved to be a suitable platform for photocatalytic applications due to the well-maintained 0D/2D nanostructure.

NiOx films with different Ni states are prepared by decomposing the solution-derived Ni(OH)2 films in varies of atmospheres. All the NiOx films exhibit full coverage on the substrates with rough surfaces. Both the air annealing and O2 annealing result in similar film compositions, which are composed of NiO, Ni2O3 and NiOOH. While additional metallic nickel is observed in the N2-annealed sample, which is different from the pure NiO powders annealed in N2, indicating a complicated decomposition process of Ni(OH)2 in N2 atmosphere. The as-prepared NiOx films were employed as the hole transport layer of inverted planar perovskite solar cells. Owing to the existence of metallic nickel, an obvious performance degradation is observed for device based on the N2-annealed sample. Finally, the champion power conversion efficiency (PCE) of 14.55% is achieved on the device based on the air-annealed NiOx film, which should be attributed to the slightly higher content of NiOOH compared to the O2-annealed sample.

Fullerene-based derivatives passivation and TiCl4 treatment are widely used as interfacial modification methods in planar perovskite solar cells for enhancing efficiency, stability and reducing hysteresis. Although the two kinds of surface modifications have been separately reported to modify the metal oxide or even directly modify the electrodes, the resulting device performance is still moderate. Herein, we report a sequential surface modification of FTO by combining a low-temperature processed ultrathin TiOx layer with a PCBM passivation layer, synergistically affording high efficiency and mitigated hysteresis and exhibiting good reproducibility for n–i–p planar perovskite solar cells. Based on this sequential modification strategy, the modified FTO substrates can effectively facilitate electron transfer and suppress interfacial recombination. As a result, we obtain efficient perovskite solar cells with the best power conversion efficiency (PCE) of 18.26% and the stabilized PCE of 17.22%. Additionally, we demonstrate that this facile sequential surface modification method gives rise to highly reproducible device performance with the average PCE of 17.16%. Beyond that, the photocurrent hysteresis is effectively suppressed for the obtained solar cells compared with the single modified analogues owing to facilitated electron transfer at the interface.

Ag2O-Bi2Sn2O7 composites were prepared by a chemical co-precipitation method. The microstructural, morphological and optical properties of the as-prepared composites were characterized and studied. Effects of Ag2O contents on photocatalytic activity of the Ag2O-Bi2Sn2O7 composites were also investigated in detail. Compared with pure Bi2Sn2O7, the 0.03Ag2O-Bi2Sn2O7 composite exhibits the highest photocatalytic activity for the degradation of Rhodamine B aqueous solution under visible light irradiation. The enhanced photocatalytic activity of the Ag2O-Bi2Sn2O7 composite can be attributed to the existence of the Ag2O-Bi2Sn2O7 heterojunction, which is propitious to an effective separation of the photogenerated electron-hole pairs.

In this work, we report a reliable method for synthesizing (Au, Au/Ag core)/(TiO2 shell) nanostructures with their plasmonic wavelengths covering the visible light region for perovskite solar cells. The mono- and bi-metallic core-shell nanoparticles exhibit tunable localized surface plasmon resonance wavelength and function as “light tentacle” to improve the photo-electricity conversion efficiency. Plasmonic nanoparticles with different sizes and shapes, different thicknesses of TiO2 shell and Ag interlayer are found to have a strong influence on the localized surface plasmon resonance enhancement effect. The experimental photovoltaic performance of perovskite solar cells is significantly enhanced when the plasmonic nanoparticles are embedded inmesoporous TiO2 scaffolds. A champion photo-electricity conversion efficiency of 17.85% is achieved with nanoparticles (Au/Ag, λLSPR = 650 nm), giving a 18.7% enhancement over that of the pristine device (15.04%). Finite-difference time-domain simulations show that nanorod Au in mesoporus TiO2 scaffold induces the most intense electromagnetic coupling, and provides a novel emitter for photon flux in mesoporous perovskite solar cells. These theoretical results are consistent with the corresponding experimental those. Thus, enhancing the incident light intensities around 650 nm will be most favorable to the improvement of the photo-electricity conversion efficiency of perovskite solar cells.

Indium oxide (IO) has been demonstrated as an efficient and stable electron transporting layer for planar heterojunction perovskite solar cells, but dispersive pinholes in the sol-gel derived IO film limit its hole blocking capacity and corresponding device performance. In this study, we introduce an ultrathin TiOx interlayer between Indium Tin Oxide (ITO) substrate and IO film via a low temperature TiCl4 treatment method. By optimizing the process time, we obtain the optimal perovskite solar cells with a 30 min TiCl4 treatment process, showing an impressive power conversion efficiency of 16.38%. In addition, the average device efficiency is improved from 13.7% to 15.1%, which is mainly attributed to the greatly improved fill factor. By means of investigating film roughness, pinhole effect and open circuit voltage decay, we find that the low-temperature processed TiOx interlayer efficiently enhance the hole blocking capacity of the electron transporting layer, and consequently boost the device performance.

A new ternary system consisting of ZnO nanorod/reduced graphene oxide (RGO)/CuInS2 quantum dots has been successfully prepared for photocatalytic application under visible light irradiation. Through the hybridization with the light harvesting material of CuInS2, as well as the conductivity medium RGO, the ternary composite achieves a greatly enhanced light absorption and charge transfer than that of the pristine ZnO. The photocatalytic performance of ZnO-RGO-CuInS2 is substantially elevated with an optimized content of 10% CuInS2 incorporated. The composite material of ZnO-RGO-10% CuInS2 can nearly completely degrade Rhodamine B (RhB) solution in 120 min, whereas bare ZnO itself can only degrade 20% RhB. The excellent photocatalytic performance of ZnO-RGO-CuInS2 demonstrates its promising in the photocatalytic or other extended applications. This work demonstrates a facile way to prepare integrative photosensitizer by taking advantage from the co-catalysts for more efficient and stable semiconductor based composite photocatalyst.

Annealing atmosphere strongly affects the structure of phosphorus-doped molybdenum carbide (P-Mo2C) nanodots hybridized with Ti3C2 MXene flakes and modulates its performance in the hydrogen evolution reaction. It is discovered that the nanohybrids undergo partial oxidation when they are annealed in N2, while retaining similar nanostructures when they are annealed in H2/Ar, Ar, and NH3. More importantly, compared with the nanohybrids annealed in Ar, NH3, and N2, the nanohybrid annealed in H2/Ar delivers the best HER performances, which delivers overpotentials (η10) of 172 and 219 mV at 10 mA cm−2, and Tafel slopes of 56.2 and 63.3 mV dec−1 in 0.5 M H2SO4 and 1.0 M KOH, respectively. The excellent HER performance could be attributed to optimal P-Mo2C nanodots for more accessible reactive sites, highly conductive Ti3C2 matrix for accelerated electron transfer, as well as N-doped carbon for more active centers. This work may shed light on developing the promising MXenes-based electrocatalysts by manipulating annealing atmosphere.