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Photocatalytic overall water splitting (POWS) is a promising route for converting solar energy into green and sustainable energy. Herein, we report a facile hydrothermal approach to fabricate polyhedron BiVO4 by Mo and Yco-doping (MYB) photocatalysts with suitable band gap for POWS. The MYB exhibited enhanced visible light-driven POWS activities in comparison with that of as-prepared BiVO4, Y-BiVO4 and M-BiVO4, with the maximum H2 and O2 evolution rate of 34.7 and 17.4 μmol·h−1·g−1, respectively. The optimum activity of the catalyst was controlled by adjusting Mo content of MYB. The photodeposition of Pt shows that there are special separation reduction and oxidation centers on the surface of MYB. Electrochemical experiments further confirmed the enhanced charge separation of MYB. MYB photocatalyst has small particle size, unique polyhedral structure, large specific surface area and high (103) and (200) surface exposure, thus improving POWS performance, high electron transfer efficiency and effective separation of photogenerated electron–hole pairs. Because of the doping of Mo and Y elements, the electronic structure of the catalyst is altered, enhancing light absorption and reducing the recombination of photogenerated electron–hole pair. The current study revealed that the MYB products could serve as cost-effective and stable photocatalysts for POWS. [ABSTRACT FROM AUTHOR]

Methylammonium chloride (MACl) additive is almost irreplaceable in high‐performance formamidine perovskite photovoltaics. Nevertheless, Some of the problems that can arise from adding MACl are rarely mentioned. Herein, it is proposed for the first time that the addition of MACl would cause the non‐stoichiometric ratio in the perovskite film, resulting in the halogen vacancy. It is demonstrated that the non‐synchronous volatilization of methylamine cations and chloride ions leads to the formation of halogen vacancy defects. To solve this problem, the NH4HCOO is introduced into the perovskite precursor solution to passivate the halogen vacancy. The HCOO− ions have a strong force with lead ions and can fill the halogen vacancy defects. Consequently, the champion devices' power conversion efficiency (PCE) can be improved from 21.23% to 23.72% with negligible hysteresis. And the unencapsulated device can still retain >90% of the initial PCE even operating in N2 atmosphere for over 1200 h. This work illustrates another halogen defect source in the MACl‐assisted formamidine perovskite photovoltaics and provides a new route to obtain high‐performance perovskite solar cells. [ABSTRACT FROM AUTHOR]

We prepared ternary organic solar cells (OSCs) by incorporating the medium wavelength absorption polymer PSEHTT into the PM6:L8-BO binary system. The power conversion efficiency (PCE) is improved from 15.83% to 16.66%. Although the fill factor (FF) is slightly reduced, the short-circuit current density (JSC) and open-circuit voltage (VOC) are significantly increased at the same time. A small amount of PSEHTT has a broad absorption spectrum in the short wavelength region and has good compatibility with PM6, which is conducive to fine-tuning the photon collection and improving the JSC. In addition, the highest occupied molecular orbital (HOMO) energy level of PSEHTT is deeper than that of PM6, which broadens the optical bandgap. This study provides an effective method to fabricate high-performance ternary OSCs by using a lower concentration of PSEHTT with PM6 as a hybrid donor material, which ensures a better surface and bulk morphology, improves photon collection, and broadens the optical bandgap. [ABSTRACT FROM AUTHOR]

Electron transport layers (ETLs) are crucial for achieving efficient and stable planar perovskite solar cells (PSCs). Reports on versatile inorganic ETLs using a simple film fabrication method and applicability for both low‐cost planar regular and inverted PSCs with excellent efficiencies (>22%) and high stability are very limited. Herein, we employ a novel inorganic ZnSe as ETL for both regular and inverted PSCs to improve the efficiency and stability using a simple thermal evaporation method. The TiO2‐ZnSe‐FAPbI3 heterojunction could be formed, resulting in an improved charge collection and a decreased carrier recombination further proved through theoretical calculations. The optimized regular PSCs based on TiO2/ZnSe have achieved 23.25% efficiency with negligible hysteresis. In addition, the ZnSe ETL can also effectively replace the unstable bathocuproine (BCP) in inverted PSCs. Consequently, the ZnSe‐based inverted device realizes a champion efficiency of 22.54%. Moreover, the regular device comprising the TiO2/ZnSe layers retains 92% of its initial PCE after 10:00 h under 1 Sun continuous illumination and the inverted device comprising the C60/ZnSe layers maintains over 85% of its initial PCE at 85 °C for 10:00 h. This highlights one of the best results among universal ETLs in both regular and inverted perovskite photovoltaics. [ABSTRACT FROM AUTHOR]

Photocatalytic split water attracts tremendous research interest because of its outstanding advantages in generating clean energy. Therefore, this work reports the synthesis of Pt/TiO2@CdS/Co3O4 hollow core–shell nanocomposites using a hard template method. The resulting material was then used for photo-induced spontaneous water splitting. The rationally designed hollow core–shell structure of this material not only enhanced the light collection capacity but also improved the separation efficiency of photogenerated carriers owing to its TiO2/CdS heterojunction. The presence of the Pt and Co3O4 catalysts in our novel material resulted in 63.2 and 29.7 μmol/g of H2 and O2 yields, respectively. Our work provides insights into conversion efficiency improvements during visible light-assisted catalytic water splitting. [ABSTRACT FROM AUTHOR]

Understanding the function of moisture on perovskite is challenging since the random environmental moisture strongly disturbs the perovskite structure. Here, we develop various N2-protected characterization techniques to comprehensively study the effect of moisture on the efficient cesium, methylammonium, and formamidinium triple-cation perovskite (Cs0.05FA0.75MA0.20)Pb(I0.96Br0.04)3. In contrast to the secondary measurements, the established air-exposure-free techniques allow us directly monitor the influence of moisture during perovskite crystallization. We find a controllable moisture treatment for the intermediate perovskite can promote the mass transportation of organic salts, and help them enter the buried bottom of the films. This process accelerates the quasi-solid-solid reaction between organic salts and PbI2, enables a spatially homogeneous intermediate phase, and translates to high-quality perovskites with much-suppressed defects. Consequently, we obtain a champion device efficiency of approaching 24% with negligible hysteresis. The devices exhibit an average T80-lifetime of 852 h (maximum 1210 h) working at the maximum power point. Perovskite structure is disturbed by environmental moisture, limiting the device performance. Here, Wei et al. monitor the effect of moisture during the growth by N2-protected characterization techniques, and obtain an operationally stable perovskite solar cell with efficiency approaching 24%. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) employing organic-inorganic halide perovskite as active layers have attracted the interesting of many scientists since 2009. The power conversion efficiency (PCE) have pushed certified 25.2% in 2019 from initial 3.81% in 2009, which is much faster than that of any type of solar cell. In the process of optimization, many innovative approaches to improve the morphology of perovskite films were developed, aiming at elevate the power conversion efficiency of perovskite solar cells (PSCs) as well as long-term stability. In the context of PSCs research, the perovskite precursor solutions modified with different additives have been extensively studied, with remarkable progress in improving the whole performance. In this comprehensive review, we focus on the forces induced by additives between the cations and anions of perovskite precursor, such as hydrogen bonds, coordination or some by-product (e.g., mesophase), which will lead to form intermediate adduct phases and then can be converted into high quality films. A compact uniform perovskite films can not only upgrade the power conversion efficiency (PCE) of devices but also improve the stability of PSCs under ambient conditions. Therefore, strategies for the implementation of additives engineering in perovskites precursor solution will be critical for the future development of PSCs. How to manipulate the weak forces in the fabrication of perovskite film could help to further develop high-efficiency solar cells with long-term stability and enable the potential of future practical applications. [ABSTRACT FROM AUTHOR]

Abstract Ternary organic solar cells (OSCs) are fabricate using a single wide-bandgap poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b0]dithiophene))-alt-(5,5-(10,30-di-2-thienyl-50,70-bis(2-ethylhexyl)benzo[10,20-c:40,50-c0]dithiophene-4,8-dione))] (PBDB-T) as the donor material and 3,9-bis (2-methylene-(3-(1,1-dicyanomethylene)-indanone)-5,5,11,11-tetrakis (4-hexylphenyl)-dithieno[2,3-d:2′, 3′-d′]-s-indaceno[1,2-b:5,6-b']dithiophene) (ITIC) as the acceptor and poly[[N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-(3,3′-difluoro-2,2′-bithiophene)-5,5′-diyl] (F N2200) as third component materials. Due to the strong absorption ability at the short-wavelength region. The best power conversion efficiency (PCE) of 10.9% is achieve for the OSCs via incorporating 10 wt% F N2200 in blend-acceptor materials, with an enhance the short-circuit current (J SC) of 17.6 mA cm−2, fill factor (FF) of 68.0% and stable open-circuit voltage (V OC) of 0.91 V relative to binary OSCs. The short-wavelength absorption windows of F N2200 is favourable the harvesting of as many as possible photons and the enhance exciton dissociation ratio at the ITIC/F N2200 interface due to the deeper LUMO energy level of F N2200 relative to ITIC molecule. Meanwhile, the incorporation small amount of F N2200 is weaken monomolecular recombination and bimolecular recombination under open-circuit and short-circuit conditions respectively and enhance the charge carrier mobility. The use of PBDB-T as donor and the blend of ITIC and F N2200 as an electron acceptor provides a useful strategy for exploring high-performance ternary OSCs. Highlights • Ternary OSCs were fabricated with F N2200 as third component materials. • The ternary photoactive layer is weaken charge carrier recombination. • The improvement of exciton-dissociation at the PBDB-T/acceptor interface. • The enhanced photovoltaic performance, especially under weak light intensity. [ABSTRACT FROM AUTHOR]

Abstract We describe a ternary photoactive layer based on PffBT4T-2OD as a donor with a blend of dihydronaphthyl-based C60 bisadduct (NCBA) and PC 71 BM as the acceptor. It offers ideal exciton dissociation, an ideal charge-carrier recombination and photovoltaic performance relationship, and improves the power-conversion efficiency (PCE) and stability of polymer solar cells (PSCs). NCBA has a broad visible-light absorption spectrum and shallower lowest unoccupied molecular orbital (LUMO) energy levels, which enhance exciton dissociation and charge-carrier transport and suppress charge-carrier recombination. This remarkably increases the photocurrent density and fill factor. An optimized PCE of 9.79% was achieved for the ternary PffBT4T-2OD:NCBA:PC 71 BM(1:0.24:0.96)-based PSCs. The mechanism was exciton dissociation at the PffBT4T-2OD/NCBA, PffBT4T-2OD:PC 71 BM, and NCBA/PC 71 BM interfaces. This simultaneously enhances the exciton-dissociation ratio and charge-carrier transport. Meanwhile, PSCs with 20% NCBA as third-component materials exhibit improved thermal stability and photo-stability leading to a lower ratio of PCE under long-time thermal-annealing and visible-light-illuminated treatment. This work indicates that NCBAs are third-component materials that significantly improve PSC performance. Highlights • Ternary PSCs were fabricated with NCBA as third component materials. • The ternary photoactive layer is weaken charge carrier recombination. • The improved exciton-dissociation at the donor–blend acceptor interface. • The enhanced photovoltaic performance, thermal stability and photo stability. [ABSTRACT FROM AUTHOR]

Abstract Zinc oxide (ZnO) as an electron transport material has been used in regular planar perovskite solar cells (PSCs). Herein, ZnO nanoparticles serve as an additive directly in perovskite active layer in order to fabricate a bulk-heterojunction inverted planar PSC. The CH 3 NH 3 PbI 3-x Cl x :ZnO bulk heterojunction is prepared by mixing ZnO nanoparticles into CH 3 NH 3 PbI 3-x Cl x precursor solution. ZnO nanoparticles act as catalytic centers and induce the growth of perovskite grains leading to the formation of large-size perovskite crystals. Remarkably, hysterysis-free power conversion efficiency of 17.26% is achieved when precisely control the concentration of ZnO nanoparticles in CH 3 NH 3 PbI x Cl 3-x :ZnO bulk heterojunction active layer. The presence of ZnO nanoparticles in the perovskite films enhances the conductivity and electron mobility. Efficient charge injection of CH 3 NH 3 PbI x Cl 3-x :ZnO film can improve charge extraction in the PSCs. Moreover, the PSCs with CH 3 NH 3 PbI x Cl 3-x :ZnO bulk heterojunction exhibit high fill factor of 77.3% and short current density of 22.71 mA cm−2, which is attributed to improved perovskite quality. The bulk heterojunction structure is fabricated by combining perovskite and metal oxides, which is of great importance to the development and commercialization of PSCs in the future. Graphical abstract Image 1 Highlights • A CH 3 NH 3 PbI 3-x Cl x :ZnO bulk heterojunction exits in the perovskite solar cell. • ZnO nanoparticles improve light harvesting efficiency of perovskite solar cell. • ZnO nanoparticles lead to the formation of large-size perovskite crystals. • ZnO nanoparticles improve conductivity and electron mobility of perovskite film. [ABSTRACT FROM AUTHOR]

A low-temperature, solution-processed molybdenum oxide (MoO X ) layer and a facile method for polymer solar cells (PSCs) is developed. The PSCs based on a MoO X layer as the hole extraction layer (HEL) is a significant advance for achieving higher photovoltaic performance, especially under weaker light illumination intensity. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements show that the (NH 4 ) 6 Mo 7 O 24 molecule decomposes and forms the molybdenum oxide (MoO X ) molecule when undergoing thermal annealing treatment. In this study, PSCs with the MoO X layer as the HEL exhibited better photovoltaic performance, especially under weak light illumination intensity (from 100 to 10 mW cm −2 ) compared to poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)-based PSCs. Analysis of the current density-voltage ( J - V ) characteristics at various light intensities provides information on the different recombination mechanisms in the PSCs with a MoO X and PEDOT:PSS layer as the HEL. That the slopes of the open-circuit voltage ( V OC ) versus light illumination intensity plots are close to 1 unity ( kT/q ) reveals that bimolecular recombination is the dominant and weaker monomolecular recombination mechanism in open-circuit conditions. That the slopes of the short-circuit current density ( J SC ) versus light illumination intensity plots are close to 1 reveals that the effective charge carrier transport and collection mechanism of the MoO X /indium tin oxide (ITO) anode is the weaker bimolecular recombination in short-circuit conditions. Our results indicate that MoO X is an alternative candidate for high-performance PSCs, especially under weak light illumination intensity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ternary PSCs were fabricated with PBDB-TF as third component materials. • The improvement of charge dynamics process of ternary photoactive layer by ternary strategy. • The improved exciton-dissociation at the donor–blend acceptor interface. In this manuscripts, a ternary polymer solar cells (PSCs) are fabricate with two "D18-series" donor (D18-Cl and D18) as blend donor and T6 as acceptor. The effects of D18-Cl and D18 in ternary PSC on the film morphology, photoelectronic properties and charge carrier dynamics were systematically investigated. By finely adjusting the D18 content, a power conversion efficiency (PCE) of 16.66 % is achieved in the optimized ternary PSCs with 35 wt% D18 in donor, resulting from significantly improved short-circuit-current density (J SC) of 26.80 mA cm−2 in comparison with those of D18-Cl:Y6 binary PSCs. The J SC of ternary PSCs monotonously increase along with the incorporation of D18, indicating that D18 is comprehensively optimal short wavelength photon harvesting compared with D18-Cl. Both D18-Cl and D18 are shown similar highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels, which is beneficial to efficient charge transport at the blend donor domain. Our work indicates that the blend of D18-Cl and D18 as blend donor and Y6 as electron acceptor to boost photovoltaic performance in the ternary PSCs. [ABSTRACT FROM AUTHOR]

Photo-annealing treatment has successfully been demonstrated in organic solar cells (OSCs) with solution-processable titanium (diisopropoxide) bis(2,4-pentanedionate) (TIPD) as an electron extraction layer; this process was shown without thermal annealing treatment. The power conversion efficiency (PCE) is quite low in the initial stage, though it dramatically increases following constant light illumination and reaches a saturated state after 9 min of light illumination. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) and ultraviolet photoemission spectroscopy (UPS) were used, and they showed that the TIPD molecules decomposed and formed stable Ti O bonds. According to photocurrent density-effective voltage curve (J ph - V eff), short-circuit current density (J SC) and open-circuit voltage (V OC) value under different light intensity, the photo-annealed TIPD-based OSCs showed efficient charge transport and suppressed charge recombination. Thus, after a fresh TIPD solution was spin-coated onto the indium tin oxide (ITO) surface and photo-annealed for 9 min, the OSCs showed the highest photovoltaic performance compared to ZnO-based OSCs. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Calcium (Ca) is not a desirable candidate as electron extraction layer (EEL) for long-term stability organic photovoltaics (OPVs) on account of its nature of active metal. In this paper, we has selected thieno[3,4-b]thiophene/benzodithiophene (PTB7) and [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) as donor and acceptor, respectively, and the device architecture is Glass/ITO/poly(ethylenedioxythiophene):polystyrene sulphonate (PEDOT:PSS)/PTB7:PC71BM/EEL/Aluminum. For comparison, tris (8-hydroxyquinoline) aluminum (Alq3) and Ca were used as EEL to reveal their influence on the performance [power conversion efficiency (PCE), short-circuit current density (J SC), open-circuit voltage (V OC) and fill factor (FF)] of the OPVs. As a result, PCE of the device with Ca as EEL rapidly reduced over 60% after three days due to the poor stability of Ca. The device with Alq3 as EEL shows favorable stability owing to the PCE moderate declined less than 30% after one month. Furthermore, PCE of the device with Alq3 as EEL was fully comparable to that with Ca as EEL. Our results indicate that Alq3 is an alternative candidate for high-performance and long-term photo-stability OPVs. [Copyright &y& Elsevier]

The ternary organic solar cells (OSCs) were fabricated with PBDB-T as donor and a blend of IEICO-4F and NC 70 BA as the acceptor and the power conversion efficiency (PCE) reaches 10.92%. Due to good compatibility and cascade LUMO level among PBDB-T, a large amount of IEICO-4F and a small amount of NC 70 BA (the ratio of IEICO-4F:NC 70 BA is 85:15), which beneficial for adjusting lowest unoccupied molecular orbital (LUMO) levels of blend acceptor and wide energy offset between the donor and acceptor materials, leading to the enhancement of the open-circuit voltage (V OC). The optimized ternary PBDB-T:IEICO-4F:NC 70 BA films is more efficient exciton dissociation and suppress charge carrier recombination than that of binary PBDB-T:IEICO-4F and PBDB-T:NC 70 BA films, leading to small energy losses. In addition, this approach maintains PCE without sacrificing short-circuit current density (J SC) and fill factor (FF), even if the weak long and near-infrared wavelength photon harvesting. A more than 10% PCE improvement is achieve by employing a ternary strategy in comparison to PBDB-T:IEICO-4F-based binary OSCs with a PCE of 9.87%. Simultaneously, the optimized ternary PBDB-T:IEICO-4F:NC 70 BA OSCs exhibit the excellent thermal stability and 78.8% initial PCE under thermal annealing treatment at 80 °C for 20 h. • The ternary OSCs with blend acceptor achieved a PCE of 10.92%. • Around 10% PCE improvement is obtained by employing ternary strategy. • The improvement of exciton-dissociation at the Donor/blend acceptor interface. • The simultaneously enhance performance and stability for ternary OSCs. [ABSTRACT FROM AUTHOR]

All-inorganic CsPbBr 3 perovskite has triggered great interests in photovoltaic field owing to its superior stability. However, the uncontrollable CsPbBr 3 film growth in solution always leads to a poor film quality with low phase-purity as well as many surface and bulk defects. Herein, we demonstrate an environmentally friendly non-solution route to fabricate high-quality CsPbBr 3 films for carbon-based planar perovskite solar cells. By precisely tuning the thickness ratio of the evaporated CsBr to PbBr 2 precursors (r), the dominant phase conversion of the cesium lead bromide perovskites from PbBr 2 -rich CsPb 2 Br 5 (r ≤ 12:7) to CsPbBr 3 (r = 12:8), and further to CsBr-rich Cs 4 PbBr 6 (r ≥ 12:9) are achieved. The optimized CsPbBr 3 perovskites are highly phase-pure and crystallized with ultra-high light absorption ability. The as-prepared CsPbBr 3 films also exhibit a dense and uniform morphology with large grain sizes and monolayer-vertical aligned grains. The corresponding devices deliver a champion PCE of 7.58%, which is an excellent efficiency among carbon-based CsPbBr 3 cells with evaporated CsPbBr 3 light absorbers. The large-area (1 cm2) devices also achieve an efficiency of 6.21%. Moreover, the unencapsulated CsPbBr 3 devices present superior moisture and thermal stabilities. Our work provides a facile approach to fabricate high-quality and large-area CsPbBr 3 films for highly efficient solar cells, light-emitting diodes and photodetectors. Image 1 • A sequential evaporation method is devised to prepare high-quality CsPbBr 3 films. • An excellent PCE of 7.58% is achieved for carbon-based CsPbBr 3 PSCs. • A PCE of 6.21% is obtained for large-area devices with an active area of 1 cm2. • Superior moisture and thermal stabilities are obtained for the devices. • The whole production costs of the devices are very low. [ABSTRACT FROM AUTHOR]

α-Formamidinium lead iodide (α-FAPbI 3) has become one of the most promising candidate materials for stable perovskite solar cells (PSCs) owing to their outstanding optoelectronic properties and high thermal stability. The crystallinity of the active layer of perovskite is essential to the performance of perovskite solar cells. In this paper, we added lead acetate Pb(Ac) 2 as a grain growth agent into the perovskite precursor solution to prepare high-efficiency and stable perovskite solar cells. It was revealed that the crystals of Pb(Ac) 2 -modified film grew selectively along the [200] direction and that the FAPbI 3 active layer grains were arranged neatly and densely, due to the significant influence of a moderate amount of weakly acidic Ac- on the crystal growth of FAPbI 3. The relative reduction in its grain boundaries led to the decrease in the grain boundary impedance, and it was easier for electrons to perform long-range migration in the perovskite active layer. The beneficial effects of Pb(Ac) 2 were further expiored by femtosecond Fs-TA measurements and density of states (tDOS) analysis, where the carrier lifetimes τ 2 was increased from 482.4 ps to 1340 ps, and the trap density of film states was significantly reduced. The filling factor (FF) and power conversion efficiency (PCE) were increased from 76.5% and 19.7–81.1% and 21.8%, respectively, the Pb(Ac) 2 devices were placed in air for 800 h for the light aging test, and the test results still maintained 90% of the original efficiency, which improved the stability of FAPbI 3 crystals. • Pb(Ac) 2 as an additive to modulate the crystalline quality of perovskite active layer films. • Perovskite solar cell defect reduction and carrier lifetime increase by Pb(Ac) 2 modification. • The Pb(Ac) 2 -modified active layer grains have preferential orientation and orderly arrangement. • 81.1% filling factor and 21.8% efficiency are achieved for a single PSC cell with excellent stability. [ABSTRACT FROM AUTHOR]