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Minimizing surface defect is vital to further improve power conversion efficiency (PCE) and stability of inorganic perovskite solar cells (PSCs). Herein, we designed a passivator trifluoroacetamidine (TFA) to suppress CsPbI

Paddy soil and irrigation water are commonly contaminated with hexavalent chromium [Cr(VI)] near urban industrial areas, thereby threatening the safety of agricultural products and human health. In this study, we develop a porous and high specific area bone char (BC) to support nanoscale zero-valent iron (nZVI) and apply it to remediate Cr(VI) pollution in water and paddy soil under anaerobic conditions. The batch experiments reveal that BC/nZVI exhibits a higher removal capacity of 516.7 mg/(g•nZVI) for Cr(VI) than nZVI when normalized to the actual nZVI content, which is 2.8 times that of nZVI; moreover, the highest nZVI utilization is the nZVI loading of 15% (BC/nZVI15). The Cr(VI) removal efficiency of BC/nZVI15 decreases with increasing pH (4 – 10). Coexisting ions (phosphate and carbonate) and humic acid can inhibit the removal of Cr(VI) with BC/nZVI15. Additionally, BC exhibits a strong advantage in promoting Cr(VI) removal by nZVI compared to the widely used biochar and activated carbon. Our results demonstrate that reduction and coprecipitation are the dominant Cr(VI) removal mechanisms. Furthermore, BC/nZVI15 shows a significantly higher reduction and removal efficiency as well as a strong anti-interference ability for Cr(VI) in paddy soil, as compared to nZVI. These findings provide a new effective material for remediating Cr(VI) pollution from water and soil.

An all-inorganic CsPbI3 perovskite has exhibited some special excellent properties particularly high thermal stability and potential for tandem solar cells, yet its poor humidity stability and grai...

Although silver (Ag) substitution offers several benefits in eliminating bulk defects and facilitating interface type inversion for Cu2ZnSn(S,Se)4 (CZTSSe) photovoltaic (PV) technology, its further development is still hindered by the fairly low electrical conductivity due to the significant decrease of acceptors amount. In this work, a versatile Li–Ag co-doping strategy is demonstrated to mitigate the poor electrical conductivity arising from Ag through direct incorporating Li via postdeposition treatment (PDT) on top of the Ag-substituted CZTSSe absorber. Depth characterizations demonstrate that Li incorporation increases p-type carrier concentration, improves the carrier collection within the bulk, reduces the defects energy level as well as inverts the electric field polarity at grain boundaries (GBs) for Ag-substituted CZTSSe system. Benefiting from this lithium-assisted complex engineering of electrical performance both in grain interior (GI) and GBs, the power conversion efficiency (PCE) is finally increased from 9.21% to 10.29%. This systematic study represents an effective way to overcome the challenges encountered in Ag substitution, and these findings support a new aspect that the synergistic effects of double cation dopant will further pave the way for the development of high efficiency kesterite PV technology.

VS2 spheres and VS2 sheets with doped compositions (Mo, Ag and graphite) were successfully prepared by one-step hydrothermal method and characterized by different techniques including X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N2 adsorption isotherms. Catalysts were applied for the depolymerization of alkali lignin. VS2 spheres exhibited lower yield of degraded lignin and bio-oil than those with VS2 sheets and VS2 flowers heated to 250 °C and held for 1.5 h with 2.0 MPa H2. The catalytic depolymerization performance was markedly affected by the dopant in the VS2 sheets, with the highest degraded lignin yield of 81.22%, achieved over 5 wt% Ag-VS2 at 290 °C under 2.0 MPa H2 for 1.5 h, yielding 61.23% bio-oil. The VS2-based catalysts show excellent selectivity in the interruption of the lignin structure and target production of bio-oil. The bio-oil showed that the relevant contents of a phenolic-type compound changes significantly according to the dopant in the VS2 catalyst.

All-inorganic cesium lead triiodide (CsPbI

Green/sustainable catalyst system is highly desirable, and to this end, biopolymer based functional hydrogel has received much attention due to its various unique properties. Herein, a palladium nanoparticle catalyst supported by natural polymer-based hydrogel, consisting of cationic nanocellulose and alginate (Pd NPs@CNCC–AHB) was prepared and its efficient catalytic applications were demonstrated for dye removal and Suzuki coupling reaction. Cationic nanocellulose was prepared based on (1) periodate oxidation, (2) Schiff base reaction, then the hydrogels were synthesized based on the ionic interaction (Ca2+) and electrostatic interactions of cationic nanocellulose and anionic alginate. Subsequently, Pd NPs formed in situ within the hydrogel based on green synthesis, consisting of PdCl2 adsorption into the CNCC–AHB hydrogel, and carbonyl-induced reduction of Pd2+ to Pd0 at 80 °C (carbonyl groups of nanocellulose as a result of periodate oxidation). CNCC here acted as the support/stabilizer and reducing agent for the preparation of Pd NPs. The TEM image shows the average diameter of Pd NPs is ~ 9 nm inside the CNCC–AHB hydrogel matrices. The as-prepared Pd NPs@CNCC–AHB hydrogel bead catalyst showed excellent performance for methylene blue in both batch and continuous systems. Also, a high catalytic performance (as high as 99% yield after 2 h) for the Suzuki reaction was obtained. The recyclability of the hydrogel catalyst was investigated. The palladium nanoparticle loaded cationic nanocellulose–alginate hydrogel (Pd NPs@CNCC–AHB) catalyst system has great potential for catalytic applications.

Material crystallinity is the overriding factor in the determination of the photoelectric properties of absorber materials and the overall performance of the photovoltaic device. Nevertheless, in t...

Alkaline darkening has a negative effect on chemimechanical pulps produced from various eucalypt chips. For instance, the pulp’s brightness has been found to drop rapidly when alkali addition exceeds its optimum amount. Therefore, to compare the effects of different media on brightness gain, eucalypt mechanical pulps were bleached using a typical peroxide bleaching sequence in a water medium and in an ethanol-water (E/W) medium. Various pulp brightness levels and changes of residue chemicals in the spent bleaching liquors were investigated. Compared to water medium, the net brightness gain notably increased when using the E/W medium at the same chemical dosages. The rate of pulp brightness loss caused by increasing alkali dosage dropped in the E/W medium. Analyses based on ultraviolet-visible diffuse reflectance spectra of bleached pulps, as well as gel permeation chromatography and pyrolysis-gas chromatography-mass spectrometry spectra of the residues in the spent bleaching liquors, indicated that the contributions to brightness improvement from ethanol-water media could be explained by the selective dissolution and removal of phenolic- or guaiacyl-structured lignin fragments that result in the formation of chromophoric groups under alkaline conditions.

Cu2ZnSn(S,Se)4 (CZTSSe) solar cells have been receiving considerable attention in recent years, owing to their low cost and toxicity as well as a high abundance of their constituent elements. Solution-based (mainly precursor solution) methods have been widely used in the fabrication of CZTSSe-based thin film solar cells. Though most record solar cells since 2009 have been achieved using solution-based methods, carbonaceous residues are always formed during post deposition treatment (PDT). These carbonaceous residues are detrimental to grain growth of CZTSSe to form large grains. The presence of unwanted small grain layers will increase the series resistance and reduce the fill factor of the solar cell, thus consequently decreasing the efficiency of CZTSSe solar cells. Herein, we propose “green” supercritical carbon dioxide (SCCO2) treatment to overcome the challenge of carbonaceous residues. FT-IR, SEM, XRD and Raman characterization studies were used to confirm the reduction of carbonaceous residues in CZTSSe films. The solar cell fabricated from a selenized CZTSSe precursor film with SCCO2 treatment under optimal conditions showed the best conversion efficiency of 11.23% (VOC = 0.456 V, JSC = 36.6 mA cm−2, FF = 67.1%). To the best of our knowledge, this is the first report on boosting the efficiency of solution-based CZTSSe solar cells by using SCCO2 treatment. In addition, this unique SCCO2 treatment may also bring forth new ideas for other solution-based optoelectronic devices.

Additional elements in Cu2ZnSn(S,Se)4 (CZTSSe) absorber layers present a viable strategy to improve the performance of thin film solar cells. In this study, heterovalent cation doping by partially substituting metal cations with Ga3+ is explored by constructing a sandwich-like configuration. We demonstrated that a low doping level of Ga3+ can be successfully incorporated into the host lattice of CZTSSe to form a homogeneous Cu2ZnSn(Ga) (S,Se)4 (CZTGSSe) alloy material. Characterization was performed using SEM, EDS, XRD, Raman spectroscopy, and XPS, which showed that the material fabricated by this heterovalent cation doping method expressed high phase purity, appropriate valence components, and suitable optical bandgap, which are vital for high performance solar cells. As a result, the champion device achieves stabilized efficiency as high as 10.80%, improved by nearly 28% compared with only 8.43% for the reference device.

The performance of many emerging multinary chalcogenides for photovoltaic (PV) applications has been considerably inferior to the Shockley–Queisser limit, and one of the main reasons for this is the existence of various detrimental deep-level defects and defect clusters. Among them, the development of kesterite-based Cu2ZnSn(Sx,Se1−x)4 (CZTCh) solar cells is currently hindered by a large open-circuit voltage deficit (Voc,def). Much of this Voc,def could be ascribed to the abundant cation disorder and defect clusters in the CZTSSe absorber layer, which is the origin of band-tail states caused by electrostatic potential fluctuations. To deal with the above intractable issues encountered in kesterite-like materials, a partial or complete cation substitution strategy offers a viable pathway to alter the characteristics of such deleterious defects and defects clusters, namely, (i) partial cation substitution can introduce ionic-size mismatch for alleviating antisite disorder and/or detrimental defect clusters to mitigate a large Voc,def and (ii) complete cation substitution can be expected to eliminate notorious band-tail states. This can foster the development/exploration of many emerging multinary chalcogenides beyond the kesterite-based CZTSSe for PV applications. In this review, we summarize the above recent efforts and attempts in both state-of-the-art experimental studies and gaining new theoretical insights to alleviate the problems associated with CZTSSe, as well as learn a lesson for applying to other promising chalcogenide PV materials. In addition, the record efficiencies for cation-substituted kesterite and related chalcogenides PV devices reported till date have been summarized in this review. Finally, a summary and outlook are provided on the current research trends in relation to improving kesterite-based devices, as well as the exploration of related chalcogenides PV materials.

Knowledge Graph is a semantic network that reveals the relationship between entities, which construction is to describe various entities, concepts and their relationships in the real world. Since knowledge graph can effectively reveal the relationship between the different knowledge items, it has been widely utilized in the intelligent education. In particular, relation extraction is the critical part of knowledge graph and plays a very important role in the construction of knowledge graph. According to the different magnitude of data labeling, entity relationship extraction tasks of deep learning can be divided into two categories: supervised and distant supervised. Supervised learning approaches can extract effective entity relationships. However, these approaches rely on labeled data heavily resulting in the time-consuming and laborconsuming. The distant supervision approach is widely concerned by researchers because it can generate the entity relation extraction automatically. However, the development and application of the distant supervised approach has been seriously hindered due to the noises, lack of information and disequilibrium in the relation extraction tasks. Inspired by the above analysis, the paper proposes a novel curriculum points relationship extraction model based on the distant supervision. In particular, firstly the research of the distant supervised relationship extraction model based on the sentence bag attention mechanism to extract the relationship of curriculum points. Secondly, the research of knowledge graph construction based on the knowledge ontology. Thirdly, the development of curriculum semantic retrieval platform based on Web. Compared with the existing advanced models, the AUC of this system is increased by 14.2%; At the same time, taking "big data processing" course in computer field as an example, the relationship extraction result with F1 value of 88.1% is realized. The experimental results show that the proposed model provides an effective solution for the development and application of knowledge graph in the field of intelligent education.

Although there have been reports of separate studies of photon-enhanced and plasmon-enhanced light harvesting to improve perovskite solar cell (PSC) efficiency, there are none that have achieved simultaneous enhancement in both photonic and plasmonic effects in PSCs. In this work, we designed a layer of tapered coaxial humps (TCHs) to harvest both in PSCs. The light absorption behavior of the textured perovskite layer in PSCs was systematically investigated through the finite element method (FEM). The calculation results show that the TCH-textured perovskite layer absorbs 67.6 % of visible light under AM 1.5G solar irradiation, a 21.8 % increase relative to the planar reference cell without TCHs. Using this design, a perovskite thickness of only 106 nm is needed to realize the full light absorption that normally requires 300-nm-thick perovskite without TCHs. To reveal the mechanism of light absorption enhancement, the specific field distributions were studied. We demonstrated that different photonic modes and plasmonic modes collectively result in remarkable light absorption enhancement in the 500-800 nm wavelength range. The textured PSCs reported herein provide an effective method to decrease Pb-based perovskite consumption and realize angle-insensitive and ultrathin PSCs.

The nonradiative charge recombination caused by surface defects and inferior crystalline quality are major roadblocks to further enhancing the performance of CsPbI

Cu(In,Ga)Se2 (CIGSe) based solar cells have received considerable interests because they have reached the commercialization stage. High efficiency CIGSe based solar cells are often fabricated via post deposition treatment (PDT) with alkali metal element incorporation. In this work, we present an effective and low-cost way of Na-incorporation for photoelectric conversion efficiencies (PCE) promotion of CIGSe solar cells. Soda-lime glass (SLG) was used as both substrate and cover during the PDT procedure for Na doping. The effects of different substrate and cover on the grain size and phase composition of CIGSe films were studied in detail. The Na- incorporation from SLG significantly improved the grain growth, charge carrier density and Voc of CIGSe solar cells. At last, a best 11.53% PCE CIGSe solar cell was achieved at optimal condition.

The highest efficiencies for both rigid and flexible Cu2ZnSn(S,Se)4 (CZTSSe) solar cells are still far behind the theoretical values. This is mainly due to band tailing in absorber and a large recombination near absorber/Mo interface that block the carrier transportation and lead to Voc and FF degradation, which are mostly noticeable in flexible solar cells. In this paper, CZTSSe thin films were prepared on flexible Mo substrates by green solution-based method followed by selenization. By optimizing selenization conditions (selenization time and temperature), dense and well crystallized CZTSSe thin films without micro-cracks were obtained at 550 °C for 12 min. The best efficiency of 6.78% can be achieved with Voc and FF enhanced to 390.43 mV and 57.71%. The dramatic reductions in ideal factor A, series resistance RS, the mismatch Δ(Eg-PL) and potential fluctuation γ indicate that band tailing and recombination are significantly reduced. The performance degradation with bending radius and cycles is studied for the first time among CZTSSe solar cells. Results indicate long-term stability at repeatable release–stretch cycles. The flexible CZTSSe solar cells with high stretch ability shed light on the development of flexible solar cells.

The brightness of bleached bamboo chemo-mechanical pulp (CMP) is often too low to be used as a furnish in value-added paper products. In this study, preliminary optimization of various parameters of a modified hydrogen peroxide (H2O2) bleaching procedure for bamboo CMP pulps was performed using the inclusion of ethanol in the bleaching medium (IEBM). Compared with a conventional bleaching method, this modified process is aimed at improving bleaching efficiency and brightness ceiling of bamboo CMP with the proper usage of chemicals. The CMP was bleached to a brightness of 74.2% ISO at the usage level of 12% H2O2, which shows it increased by 7.4% ISO compared with the conventional method. For a brightness target of 72.0% ISO, bleaching with the IEBM method reduced the H2O2 consumption by approximately 60%. In addition, a higher activation energy of H2O2 for the IEBM method was calculated to be 23.3 kJ/mol, which was increased by 3.3 kJ/mol compared with the conventional method.

The Z-scheme heterojunction-based photocatalyst often has excellent degradation activity for volatile organic compounds (VOCs). Herein, through unique reduction reaction, we developed a novel MnO2 photocatalyst that has a very low conduction band potential (-1.09 V), compared with those reported MnO2 in the literature. The key experimental evidence was from its XRD results showing much higher content of crystal face (1 1 0) in reference to that of standard α-MnO2 (No. 44–0144). Subsequently, a novel biochar/MnO2/g-C3N4 photocatalyst (C/CN/Mnx) was synthesized and displayed that the best formaldehyde degradation (91.78%) is 3.34 times that of g-C3N4 (27.51%) in air containing 0.5 mg L-1 formaldehyde at 3 h. Due to the favorable band potentials, the excited electrons of g-C3N4 combine with the holes of MnO2, thereby retaining low-potential electrons of MnO2, and these electrons from g-C3N4 and MnO2 can be effectively transferred to biochar so that their recombinations are minimized. The introduction of 5 mmol MnO2 can increase the singlet oxygen (1O2) concentration (2.78 × 1011 mm−3) of the photocatalyst by>4 times under visible light irradiation. This MnO2-based Z-scheme photocatalyst provides a platform technology for the photocatalytic degradation of VOCs.

VS

The Se content in a Cu2ZnSn(S, Se)4 absorber layer has a significant impact on the electronic properties, but it is rather challenging to control the Se/(S + Se) ratio due to a complicated selenization process. Here, a low-toxicity thiol/amine-based solution process was developed to tune the Se content in a Cu2ZnSn(S, Se)4 absorber layer to an optimal value by ingeniously controlling the SeO2 in the precursor solution. We demonstrated that the crystal growth and the band gap of Cu2ZnSn(S, Se)4 thin films are affected by the Se/(S + Se) ratio. By this approach, the open-circuit voltage deficit (Voc,def) of the device was effectively decreased, and the short-circuit density (Jsc) and fill factor (FF) were remarkably improved; thus, the power conversion efficiency of the Cu2ZnSn(S, Se)4 solar cells was successfully increased from 5.6% to 9.7% for the optimal band gap (Eg = 1.13 eV).

In this study, ZnO nanotubes (ZNTs) were prepared onto fluorine-doped tin oxide (FTO) glass and used as supports for MIPs arrays fabrication. Due to the imprinted cavities are always located at both inner and outer surface of ZNTs, these ZNTs supported MIPs arrays have good accessibility towards template and can be used as sensing materials for chemical sensors with high sensitivity, excellent selectivity and fast response. Using K3[Fe(CN)6] as electron probe, the fabricated electrochemical sensor shows two linear dynamic ranges (0.02–5 μM and 10–800 μM) towards dopamine. This proposed electrochemical sensor has been applied for dopamine determination with satisfied recoveries and precision. More complex human urine samples also confirmed that the proposed method has good accuracy for dopamine determination in real biological samples. These results suggest potential applicability of the proposed method and sensor in important molecule analysis.

The introduction of a double-gallium (Ga) gradient plays a key role in pushing the performance of Cu(In,Ga)Se2 (CIGSe) solar cells to a more competitive level. In particular, the location of the front-gradient starting position strongly affects the barrier of the electron transport path, and this is not based on either significantly reducing the electron collection or decreasing the fill factor. Here we present and implement a double-Ga gradient design for CIGSe absorber layers using a diamine–dithiol solution approach. By regulating the front-gradient starting location, three CIGSe absorber layers with different Ga gradients were successfully constructed; these materials maximize solar spectrum absorption and improve the charge collection efficiency. Moreover, this facile solution-process approach does not require expensive vacuum equipment and can be applied to roll-to-roll printing technology. By combining optimal front-gradients with the back gradient, the short-circuit current has been increased by 17% and a maximum improvement in CIGSe efficiency to 13.12% achieved through adjusting the front-gradient to an optimum location.

The partial substitution of Cu+ with Ag+ into the host lattice of Cu2ZnSn(S,Se)4 thin films can reduce the open-circuit voltage deficit (Voc,deficit) of Cu2ZnSn(S,Se)4 (CZTSSe) solar cells. In this paper, elemental Cu, Ag, Zn, Sn, S, and Se powders were dissolved in solvent mixture of 1,2-ethanedithiol (edtH2) and 1,2-ethylenediamine (en) and used for the formation of (Cu1–xAgx)2ZnSn(S,Se)4 (CAZTSSe) thin films with different Ag/(Ag + Cu) ratios. The key feature of this approach is that the impurity atoms can be absolutely excluded. Further results indicate that the variations of grain size, band gap, and depletion width of the CAZTSSe layer are generally determined by Ag substitution content. Benefiting from the Voc enhancement (∼50 mV), the power conversion efficiency is successfully increased from 7.39% (x = 0) to 10.36% (x = 3%), which is the highest efficiency of Ag substituted devices so far.

The doping of indium into absorber layer has been proven to be beneficial for hybrid buffer structured Cu 2 ZnSn(S, Se) 4 (CZTSSe) solar cells, but it is difficult to precisely control the doping content only relying on In diffusion from In 2 S 3 emitter. Herein, we use the solution method to prepare In-substituted CZTSSe layer by directly doping In 2 Se 3 into metal chalcogenides precursor solution. The doping content can be precisely controlled and the influences of indium doping on cell performance are systematically discussed. Mott-Schottky and resistivity measurements indicate that the carrier concentration and charge transport process are monotonically enhanced with increasing In/(In + Sn) content (0 at.%, 3 at.%, 6 at.% and 12 at.%). The improvements of series resistance also lead to a monotonic increase of fill factor ( FF ) from 52.1% to 64.8%. Due to the larger recombination at high doping content, the 6 at.% In content device finally contributes the highest power conversion efficiency of 8.47%. It is expected that a precisely controlled indium doping could further improve cell performance for efficient hybrid buffer structured devices.

The CZTS–CdS heterostructured nanocrystals were designed and synthesized via a wet chemistry approach for the first time. The p–n heterojunction between CZTS core and CdS layer facilitates a effective charge separation and a rapid charge transfer. As expected, these CZTS–CdS-heterostructured nanocrystals show enhanced photocatalytic activities for hydrogen evolution when compared with CZTS and CdS.

Although the substitution of Cu by Ag to suppress CuZn defects offers several advantages in overcoming the large open-circuit voltage (Voc) deficit for Cu2ZnSn(S,Se)4 (CZTSSe) solar cells, an excellent performance has not been achieved to date primarily due to the Fermi level pinning at the CdS/absorber interface and large recombination at the absorber/Mo interface. Herein, we developed a composition grading strategy to achieve a V-shaped Ag-graded structure with a higher Ag content on both the back and front surfaces of the (Cu,Ag)2ZnSn(S,Se)4 (CAZTSSe) layer. The key advantages of this Ag-graded structure are as follows: the higher content towards the CdS/absorber interface can create weak n-type donor defects and retard Fermi level pinning, whereas the lower content at the interlayer maintains the conductivity and light absorption; moreover, the other higher content towards Mo back contact can effectively suppress the recombination and improve the utilization of long-wave incident light. By appropriately adjusting the Ag gradient, we demonstrated a significant increase in Voc, and an unexpected conversion efficiency of 11.2% was achieved. This is the highest efficiency achieved to date for Ag-substituted CZTSSe solar cells, and the result supports a new aspect that synthesis of a composition-graded CAZTSSe absorber has great potential for future research.

CZTSSe based thin film solar cells have received considerable interests due to low material cost, suitable band gaps and high absorption coefficient of CZTSSe materials. Achieving high efficiency CZTSSe based thin film solar cells often need a high temperature selenization process that always causes Sn loss in the form of gaseous SnSe 2 . Additional Sn complement may decrease the loss of Sn during selenization process and improve the performance of fabricated CZTSSe based thin film solar cells. Here, we investigate the effect of additional Sn complement on the performance of CZTSSe based thin film solar cells fabricated from pure element solution. XRD and Raman characterizations indicate that additional Sn complement could reduce the secondary phase that may cause the voltage loss and decrease of efficiency. The solar cell fabricated with 15% additional Sn complement shows the best conversion efficiency of 8.71% (V OC =0.42 V, J SC =32.73 mA cm −2 , FF=63.19%). To the best of our knowledge, it is the highest efficiency of CZTSSe based thin film solar cells fabricated from pure element solution.

Both recombination and band-edge shift are important factors for the open-circuit voltage (Voc) improvement of metal chalcogenide hole-transport material (HTM) based perovskite solar cells, but it is still not clear that which aspect plays the dominant role in such devices. Herein, we addressed this aspect through employing the band-tunable metal chalcogenide Cu2ZnSnS4 (CZTS) QDs as HTM into perovskite solar cells. By replacing sulfur with selenium atom, the band gap of HTM was tuned from 1.64 eV to 1.14 eV and their influences on cell performances were further discussed. Though the Cu2ZnSnSe4 (CZTSe) device with higher hole transport ability could improve the fill factor (FF), its Voc was still remarkably lower than that of the CZTS device. Electrochemical impedance spectroscopy (EIS) measurements indicated that the Voc loss (45 mV) induced by recombination here was far less than the Voc differences between the two devices (140 mV). After analyzing the band level alignment at TiO2/CH3NH3PbI3/HTM heterojunction, we proposed that the Voc enhancement of CZTS device was mainly ascribed to the more downward valence band-edge shift of HTM. This further approves that developing a wide band gap material without hindering charge injection is more pressing rather than depressing recombination process for future metal chalcogenide HTM researches.

Kesterite Cu2ZnSnS4 has emerged as promising replacement for CIGS in scalable commercial thin film photovoltaics. Due to the chemical and size similarity of Cu and Zn atom, [CuZn+ZnCu] defect cluster has low formation energy and high concentration in CZTS, which resulting large amount of recombination centers. In this manuscript, (Cu1−xAgx)2ZnSnS4 nanocrystals were rationally synthesized with low defect and tuning band gap. When 2% of Cu was substituted by Ag, highest apparent carrier concentration and lowest defect were observed. The band gap of (Cu1−xAgx)2ZnSnS4 nanocrystals can be rationally controlled by adjusting Ag/(Cu+Ag) ratio. This work may contribute to enhancing the performance of Cu2ZnSnS4-based solar cells and photocatalyst in hydrogen evolution.

A novel SrTiO3/BiPO4 heterostructure with different amounts of SrTiO3 have been successfully prepared through the hydrothermal process. The photocatalysts were characterized by X-ray powder diffraction, UV–Vis diffuse reflectance spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. The photocatalytic performance was evaluated by degrading the methylene blue dye solution under UV light. Results showed that the samples displayed excellent photocatalytic degradation efficiency due to the highly efficient suppression of the recombination of electron–hole pairs. A possible mechanism of SrTiO3/BiPO4 heterojunctions was discussed. The research indicated that the as-prepared SrTiO3/BiPO4 heterogeneous photocatalyst can be used as an effective material for degrading industrial organic wastewater.

Additional elements in the Cu2ZnSn(S,Se)4 (CZTSSe) absorber layers can play a crucial role in improving the performance of thin film solar cells. In this paper, a significant performance enhancement of CZTSSe thin film solar cells was achieved by the partial substitution of the Zn2+ cation with Cd2+. A small amount of Cd2+ can be successfully incorporated into the host lattice of CZTSSe to form a homogeneous Cu2Zn1–xCdxSn(S,Se)4 (CZCTSSe) alloy material. We demonstrated that the crystal growth and the band gap of CZCTSSe thin films are affected by the Cd doping level. Additionally, the impact of Cd content on the space-charge density (Nc-v) and the depletion width (Wd) of CZCTSSe solar cells was systematically investigated. By this cation substitution approach, the power conversion efficiency of the solar cells based on the CZCTSSe absorber was successfully increased from 5.41 to 8.11% for the optimal composition (x = 5%).