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Theoretical understanding of the intrinsic mechanism for enhanced electrocatalytic activity and rational design for liquid-junction dye-sensitized solar cell (DSSC) are two persistent objectives in pursuing dual-functional counter electrode (CE) electrocatalysts with excellent electrochemical activity and stability. In the current work, we launch a strategy of synthesizing ternary platinum alloys (Pt-M-Ni, M = Co, Pd, Fe) CE and study on the synergistic effects of transition metals on catalytic activity. The preliminary results demonstrate that the ternary Pt-M-Ni alloy can markedly enhance the electrocatalytic behavior toward I 3 − , yielding maximum 8.71% efficiency in the optimized DSSC platforms in comparison with 7.10% for pure Pt based device. [ABSTRACT FROM AUTHOR]

Pursuit of cost-effective counter electrodes (CEs) with no sacrifice of photovoltaic performances is a persistent objective for dye-sensitized solar cells (DSSCs). We launch here the experimental realization of molybdenum selenide (Mo–Se) binary nanosheet CEs by a mild solution method. Due to high optical transparency, the bifacial DSSCs from cost-effective Mo–Se alloy CEs can realize electricity generation from either front or rear side. Particularly, the resultant Mo–Se alloy CEs show superior catalytic activity and charge-transfer ability toward I − / I 3 − redox electrolyte. The maximum front and rear efficiencies of 8.05% and 5.92% are recorded under simulated air mass 1.5 global irradiation, respectively. The impressive efficiency along with fast start-up, multiple start capability, and simple preparation highlights the potential application of the cost-effective and transparent Mo–Se alloy CE in robust bifacial DSSCs. [ABSTRACT FROM AUTHOR]

Pursuit of multi-interfacial counter electrodes (CEs) for enhanced triiodide (I 3 − ) reduction reaction has been a persistent objective for dye-sensitized solar cells (DSSCs). Here we report the synthesis of multilayer CEs consisting of positively charged polyaniline-graphene (PANi-G) complex and negatively charged platinum (Pt) nanoparticles. The (PANi-G/Pt) n ( n represents the bilayer number) multilayer displays multi-interfaces for I 3 − reduction and charge transfer. Moreover, the complexation between PANi and G can markedly accelerate the electron migration from G to PANi. The DSSC with (PANi-10wt‰G/Pt) 9 electrode yields an impressive power conversion efficiency of 7.45% under simulated air mass 1.5 global sunlight. The promising efficiency along with cost-effectiveness and scalable materials demonstrates the multi-interfacial CEs to be good candidates for robust DSSCs. [ABSTRACT FROM AUTHOR]

Hollow optical fiber induced dye-sensitized solar cells are made by twisting Ti wire/N719-TiO2 nanotube photoanodes and Ti wire/Pt (CoSe, Pt3Ni) counter electrodes, yielding a maximized efficiency of 0.7% and good stability. Arising from optical energy storage ability, the solar cells can generate electricity without laser illumination. [ABSTRACT FROM AUTHOR]

A new cerium conversion coating modified with the hydrolysis silane is designed for AZ31 magnesium alloy, which aims at assessing the surface characterizations and electrochemical behaviors between the cerium conversion coating with and without the silane modified. The effect of the silane addictive is studied by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The adhesion of the coatings is undertaken according to the American Society for Testing and Materials (ASTM) standard D3359-08 cross tape test. The electrochemical behavior is evacuated by polarization experiment and electrochemical impedance spectroscopy (EIS) in NaCl electrolyte. The results show that the addition of bis-[triethoxysilylpropyl] tetrasulfide (BTESPT) to loosen and porous cerium conversion coating leads to the formation of a more compact and homogenous film, higher resistance to water uptake and better adhesion to substrate. Electrochemical measurements show that, compared with the non-modified cerium conversion coating, the coating modified with the silane exhibits better anticorrosion properties. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

[Display omitted] • WO-NWs with high conductivity were fabricated to modify carbon electrodes for CsPbBr 3 PSCs. • WO-NWs enhanced hole extraction ability and reduced charge carrier recombination for PSCs. • A champion PCE of 9.17% and an ultra-high V oc of 1.592 V for CsPbBr 3 PSCs were achieved. • Ru-WO shown enhanced electrocatalytic activity and excellent operation stability for HER. • Onset overpotential of 32 mV and Tafel slope of 34 mV dec-1 were achieved by Ru-WO for HER. Solar energy is sustainable and much more abundant than other energy sources, which is considered as the most promising energy source for the future. The conversion of solar energy directly into hydrogen is an effective and promising solution to intermittency of solar energy, simultaneously addressing effective storage and transport problem. Here, we present W 18 O 49 nanowires (WO-NWs) tailored carbon electrodes to enhance hole extraction of CsPbBr 3 perovskite solar cells (PSCs) and finally achieve a champion efficiency of 9.17% with open circuit voltage (V oc) of 1.592 V. Meanwhile, we use Ru doped W 18 O 49 (Ru-WO) for robust hydrogen evolution reaction (HER) catalysts, yielding an onset overpotential of 32 mV, Tafel slope of 34 mV dec-1 and exchange current density up to 1.93×10-2 mA cm-2. Moreover, Ru-WO demonstrates excellent operation stability and steady current density up to 500 mA cm-2 over 50 h. The rapid development of CsPbBr 3 PSCs with ultra-high V oc and robust HER catalysts makes them highly promising for single-junction solar cell-driven water splitting. [ABSTRACT FROM AUTHOR]

Through passivating interfacial defects and improving energy level alignment and perovskite quality, ASF as interface modifier helps all-inorganic CsPbBr 3 PSCs achieve a champion PCE of 10.08% and excellent moisture and heat tolerance. [Display omitted] • The interface modification of ASF passivates the defects of TiO 2 and perovskite. • The energy level alignment at TiO 2 /CsPbBr 3 interface is improved by modifying ASF. • A large-grained perovskite film is formed on the ASF-modified TiO 2 ETLs. • The ASF-modified CsPbBr 3 PSCs achieve a best PCE of 10.08% and excellent stability. The interfacial modification has been considered as an effective strategy to build high-efficient and stable perovskite solar cells (PSCs) by reducing the loss of charge recombination and energy at electron transport layers (ETLs)/perovskite interface. Here, a multifunctional inorganic salt of ammonium silicofluoride (ASF) is utilized as an interfacial modifier to incorporate at TiO 2 ETLs/CsPbBr 3 perovskite interface, which decreases the surface oxygen vacancy defects of TiO 2 by its bonding with silicofluoride anion and adjusts the energy level of TiO 2 by dipole effect to minimize interfacial band difference, resulting in a promotion of electrons extraction and a reduction of energy loss. Simultaneously, the ASF modification affords a more hydrophobic TiO 2 substrate for the constitution of perovskite film with larger crystal and passivates anion defects of CsPbBr 3 film via the formation of hydrogen bonds between the H atom in ammonium cations and Br atom in perovskite, which dramatically inhibits the recombination of carriers. Finally, the all-inorganic CsPbBr 3 PSCs based on the ASF-modified TiO 2 ETL achieves a remarkable higher power conversion efficiency of 10.08%, compared to 6.84% efficiency of the control device. In addition, the long-term tolerance of the device without encapsulation towards high humidity and high temperature is significantly enhanced after interface modifying with ASF. [ABSTRACT FROM AUTHOR]

By balancing the multidentate coordination sites and structure-steric hindrance of organic passivator, the bipyridine molecule enables an enhanced efficiency up to 11.04% with voltage of 1.301 V for all-inorganic CsPbIBr 2 perovskite solar cell, demonstrating the steric-charge-dependence of conjugated passivators on π-Pb2+ bond strength. [Display omitted] • Various π-conjugated pyridine derivatives are employed to passivate perovskite film. • The effect of steric-charge-dependence of passivators on films is revealed. • A high efficiency of 11.04% has been realized for carbon-electrode based CsPbIBr 2 PSC. • The stability is significantly enhanced under persistent irradiation and storage. Intramolecular structure of interfacial passivator highly determines the bond strength with detrimental defects located at perovskite surfaces and grain boundaries. Herein, we investigate the steric-charge-dependence of various π-conjugated pyridine derivatives on electron-donating ability to passivate inorganic CsPbIBr 2 perovskite film. The primary results demonstrate that the photovoltaic performances tightly correlate with the multidentate coordination sites and structure-steric hindrance because of their synergistic regulation on intramolecular electron-cloudy density and charge extraction. Comparing to pyridine and terpyridine treated devices, the bipyridine passivated device delivers an increased efficiency of 11.04% with a high open-circuit voltage of 1.301 V and improved stability after persistent irradiation over 20 h and storage for 60 days, which is one of the highest efficiencies for carbon-based all-inorganic CsPbIBr 2 solar cells. This work provides a direction to choose ideal passivator for high-efficiency perovskite optoelectronics. [ABSTRACT FROM AUTHOR]

A transparent catalytic counter electrode (CE) with excellent properties plays an important role in the performance improvement of bifacial dye-sensitized solar cells (Bi-DSSCs). In this work, pyrrole is combined with molybdenum sulfide (MoS 2) by a refluxing technology and subsequently polymerized in situ to construct polypyrrole (PPy)-MoS 2 CEs with high transparency. And compared with the original PPy CE, the PPy-MoS 2 CE shows higher electrocatalytic activity for triiodide reduction. A superior power conversion efficiency of 9.48% under both-side irradiation is obtained for the Bi-DSSCs assembled with PPy-4 wt‰ MoS 2 complex CE, compared to 7.36% bifacial efficiency for PPy-CE based solar cell. [Display omitted] • Pyrrole-MoS 2 complexes are synthesized by a reflux process. • PPy-MoS 2 complexes are used as transparent and cost-effective CEs for bifacial DSSCs. • The incident light from rear side can compensate for the light from anode. • The DSSC assembled with PPy-MoS 2 complex CE has a high bifacial efficiency of 9.48%. [ABSTRACT FROM AUTHOR]

The soft lattice induced defective nanostructured surface of perovskite film is effectively healed and solidified by organic S-benzylisothiourea hydrochloride, significantly improving the efficiency and stability of inorganic CsPbIBr 2 perovskite solar cells. [Display omitted] • An organic molecule is employed to heal the defective surface of perovskite film. • The regulated surface energetics boosts the charge transfer. • An efficiency of 10.56% has been achieved for HTM-free CsPbIBr 2 PSC. • The long-term stability is significantly improved under air condition. Interfacial regulation to heal the soft lattice induced defective nanostructured surfaces of perovskite films plays a crucial role in determining the stability and efficiency of perovskite solar cells (PSCs). Herein, we report a facile method to strengthen and passivate the inorganic PbI 2 -excess CsPbIBr 2 surface with a multifunctional S-benzylisothiourea hydrochloride (SBTCl), which not only significantly reduces the detrimental defects through interaction between electron-donating groups and defects (as well as Cl doping as lattice "glue") but also enables straightway unobstructed hole extraction and transfer arising from the reduced work function. Consequently, a higher efficiency of 10.56% with an open-circuit voltage of 1.327 V than control device with 7.72%-efficiency is obtained for inorganic CsPbIBr 2 PSC free of hole transporting material, which is one cutting-edge value in this kind of PSC. In addition, the high hydrophobicity of SBTCl passivator hinders the permeation of moisture into perovskite film, resulting in improved long-term air-stability after storage in 5% relative humidity (RH) without encapsulation over 110 days and persistent light irradiation over 16 h in 50% RH condition. [ABSTRACT FROM AUTHOR]

Cuprous oxide (Cu2O) micro-/nanocrystals were synthesized by a simple liquid phase reduction process with copper sulfate as a copper source and glucose monohydrate as a reducer. Detailed investigations of the temperature and feeding manners of the reagents on the morphology and particle size of Cu2O were carried out. X-ray diffraction patterns, morphology observations and ultraviolet–visible diffuse reflection absorption spectra were employed to characterize the crystallinity, morphology and light response. The characterization results gave three extraordinary morphologies: short hexapods, {110} truncated octahedron, and octahedron. The photocatalytic behaviors of the Cu2O crystals were evaluated by monitoring the degradation rate of methyl orange (MO), a target dye. An order for the light photocatalytic activities toward MO was determined: octahedron (diameter 0.172 μm) ＞ short hexapods ＞ octahedron (diameter 5.530 μm) ＞ {110} truncated octahedron crystals. The bewitching structure, controllable morphology and robust photocatalytic performances as well as the easy synthesis mean that the Cu2O crystals are good candidates as light photocatalysts. [ABSTRACT FROM AUTHOR]

Polyaniline/α-RuCl3. xH2O composites were successfully synthesized by an in-situ chemical polymerization and employed as new electrode materials in supercapacitors. The synthesized composites were characterized physically by scanning electronic microscope (SEM). The electrochemical capacitance performance of these composites was investigated by cyclic voltammetry, galvanostatic charge-discharge tests and AC impedance spectroscopy with a three-electrode system in 1 mol l−1 NaNO3 aqueous solution electrolyte. The polyaniline/α-RuCl3. xH2O composites electrodes showed much higher specific capacitance, better power characteristics and were more promising for application in capacitor than pure polyaniline electrode. The effect and role of α-RuCl3. xH2O in the composite electrode were also discussed in detail. POLYM. COMPOS., 34:2142-2147, 2013. © 2013 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Highlights: [•] Ga, La codoped TiO2 nanotube arrays were synthesized for visible-light photocatalysts. [•] The photocatalytic activity is enhanced for the codoped TiO2 nanotube array. [•] An excitation energy level below the conduction band of TiO2 was formed. [ABSTRACT FROM AUTHOR]

Deposits made by the alternated deposition of polyaniline (PANI) and ZnO nanoparticles may offer interesting applications as nonvolatile memory devices owing to the specific properties of each constituent. The rectifying ratio of such devices may strongly depend on the PANI/ZnO interface and on the morphology of the (PANI/ZnO) n or (PANI/ZnO) n-PANI films. In this article we show that even if the morphology of the PEI/PSS-(PANI/ZnO) n or of the PEI/PSS-(PANI/ZnO) n-PANI films seems very heterogeneous on the basis of scanning electron micrographs, the deposits consist of clusters deposited on a continuous film. In addition, the deposits become impermeable to ferrocyanide anions after the deposition of n = 10 alternated deposition cycles, confirming the existence of a continuous and impermeable film below the observed clusters. Such deposits may find interesting properties as a nonvolatile memory device. POLYM. COMPOS. 34:1333-1341, 2013. © 2013 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Through passivating defects, improving contact and energy level alignment by interface engineering of hydrophobic DCC, the HTMs-free carbon-based CsPbBr 3 PSCs achieve a champion PCE as high as 10.16% and excellent moisture-heat stability. [Display omitted] • DCC interface engineering reduces defects and improves contact and band alignment. • The low charge recombination and E loss and enhanced charge extraction are realized. • A champion PCE of 10.16% is achieved for HTMs-free carbon-based CsPbBr 3 PSCs. • The unencapsulated PSCs exhibits excellent long-term moisture-heat tolerance. The back interface issues including numerous defects and imperfect contact, mismatched energy level are regarded as the key detrimental factors causing serious charge recombination and energy loss (E loss) and inferior charge extraction to achieve high efficiency Hole transport materials-free (HTMs-free) carbon-based Perovskite solar cells (PSCs). To address this drawback, an effective interface engineering via depositing N, N'-Dicyclohexylcarbodiimide (DCC) at PVSK/Carbon back interface is creatively implemented to passivate CsPbBr 3 surface defects through forming interaction between N atoms with lone pair electrons and uncoordinated ions (eg Pb2+ and Cs+ ions) to suppress the defect states induced non-radiative recombination and E loss. Concurrently, the smoothness and valence band of PVSK film with DCC modification are increased to improve the contact and band alignment at back interface, respectively, remarkably accelerating hole extraction and transportation and also reducing E loss as well as charge recombination. As a result, the comprehensive performance of DCC interface modified HTMs-free carbon-based CsPbBr 3 PSCs is significantly enhanced, especially the champion efficiency boosts to 10.16% from 6.60% of the control PSC. Furthermore, owing to the enhanced hydrophobicity and decreased imperfections of PVSK film with DCC modification, the optimized device without any encapsulation displays an excellent long-term stability under 85% RH air condition at 85 °C over 1200 h. [ABSTRACT FROM AUTHOR]

In this study, p-type semiconducting polymer of acid, poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), has been employed as a hole-transporting electrode to fabricate organic polymer heterojunction photovoltaic cells. The results showed that the resultant poly(3-hexylthiophene): C derivatives [6]-phenyl-C-butyric acid methyl ester (P3HT:PCBM)/PEDOT:PSS can significantly expand the light absorption range which was expected to enhance the sunlight excitation. The influences of annealing conditions and barrier layer on the photoelectric performances were investigated in detail, giving an optimized synthesis conditions: annealed temperature was at 120 °C for 90 min, the thickness of PEDOT:PSS film was approximately 3-4 μm, and the ratio of PCBM and P3HT was 1:2. The blended heterojunction consisting of PCBM and P3HT was used as charge carrier-transferring medium to replace I3-/I- redox electrolyte, showing a short-circuit current of 4.30 mA cm-2, an open-circuit voltage of 0.83 V, and a light-to-electric energy conversion efficiency of 2.37 % under a simulated solar light irradiation of 100 mW cm-2. In addition, a solid-state polymer heterojunction photovoltaic cells with a short-circuit current of 3.59 mA cm-2, an open-circuit voltage of 0.80 V, and a light-to-electric energy conversion efficiency of 1.9 % was successfully fabricated by simplifying the process. [ABSTRACT FROM AUTHOR]

Abstract: Robust Gd–La codoped TiO2 microspheres with diameter of 2∼3 μm were successfully synthesized via a hydrothermal method using poly(ethylene glycol)-block–poly(propylene glycol)-block–poly(ethylene glycol) as a template. The photocatalytic activity of the Gd–La codoped TiO2 microspheres evaluated by photodegrading methyl orange (MO) has been significantly enhanced compared to that of undoped TiO2 microspheres. Ti4+ may substitute for La3+ and Gd3+ in the lattices of rare earth oxides to create abundant oxygen vacancies and surface defects for electron trapping and dye adsorption, accelerating the separation of photogenerated electron–hole pairs and MO photodegradation. The formation of an exciton energy level below the conduction band of TiO2 from the binding of electrons and oxygen vacancies decreases the excitation energy of Gd–La codoped TiO2 microspheres, resulting in robust photocatalysts. The results suggest that Gd–La codoped TiO2 microspheres calcined at 350 °C are very promising for enhancing the photocatalytic activity of photocatalysts. [Copyright &y& Elsevier]

Abstract: A microporous hybrid polymer of poly(acrylic acid)/gelatin/polyaniline (PAA/Gel/PANI) is synthesized with a two-steps solution polymerization. Using this hybrid as polymer host, a gel-electrolyte with a high liquid absorbency of 16.45 (gg−1) and a high conductivity of 14.38mScm−1 is prepared, then a quasi-solid-state dye-sensitized solar cell (QS-DSSC) is assembled. The polymer host is characterized by scanning electron microscopy (SEM), the functional groups on the polymer are identified by Fourier transform infrared spectroscopy (FTIR) and the photovoltaic tests of the QS-DSSCs are carried out by measuring current–voltage (I–V) curves. The QS-DSSC with this hybrid gel-electrolyte achieves a light-to-electric energy conversion efficiency of 6.94%. [Copyright &y& Elsevier]

The unencapsulated all-inorganic CsPbBr 3 PSC achieves a maximized PCE of 10.10% with an excellent stability through passivation, grain size and hole mobility enhancement of perovskite film as well as boosting interfacial hole extraction by additive and interface engineering of Br-GO. [Display omitted] • Adding Br-GO maximizes the grain size and hole mobility of perovskite film. • The defects and charge recombination are evidently decreased by introducing Br-GO. • Using Br-GO as HTM helps the CsPbBr 3 + Br-GO PSCs achieve a best PCE up to 10.10%. • The unencapsulated device shows excellent tolerance to moisture and illumination. The perovskite film with large grain size and high charge mobility is critical for the improvement of the power conversion efficiency (PCE) and the operational stability of perovskite solar cells (PSCs). Herein, multifunctional brominated graphene oxide (Br-GO) is prepared and innovatively used as an effective additive to incorporate into CsPbBr 3 to form a large-grained high-quality perovskite film and to passivate defects at grain boundaries, which remarkably reduces the trap state density and carrier non-radiative recombination. Meanwhile, the hole mobility of the homogeneous CsPbBr 3 + Br-GO photoactive layer is obviously increased due to the hole acceptor properties and high carrier mobility of Br-GO, resulting in an enhanced charge separation as well as transfer and suppressed carrier radiative recombination. Moreover, the Br-GO with a downshift valence band is employed as a hole-transporting material setting at perovskite/Carbon interface to further compensate energy levels and promote hole extraction. As a consequence, a champion PCE of 10.10% with an open-circuit voltage up to 1.602 V for the optimized PSCs with a configuration of FTO/c-TiO 2 /m-TiO 2 /CsPbBr 3 + Br-GO/Br-GO/Carbon is obtained, which is much higher than 6.28% efficiency for the reference device. The unencapsulated solar cells also exhibit a remarkable tolerance toward 85% RH and long-term AM 1.5G illumination in air. [ABSTRACT FROM AUTHOR]

Through reducing the transmission of UV light and suppressing charge recombination, UV-360 as interface modifier helps the CsPbBr 3 PSCs achieve a champion PCE of 9.61% and excellent photostability and moisture-heat tolerance. • The irradiation of UV light on perovskite is filtrated by modifying UV-360. • The defects and the charge recombination of PSCs with UV-360 are markedly reduced. • A large-grained perovskite film is formed on the UV-360 modified TiO 2 ETLs. • A maximum PCE up to 9.61% is achieved for carbon-based CsPbBr 3 PSCs with UV-360. • The unsealed device shows excellent photostability and moisture-heat tolerance. The limited ultraviolet (UV) absorption of the common TiO 2 electron-transporting layers (ETLs) and the trap states density as well as imperfect contact at TiO 2 /perovskite interface have been proposed as one of the main obstacles for realizing long-term photostability and high power conversion efficiency (PCE) of perovskite solar cells (PSCs). To address this issue, an advanced and universal interface engineering has been employed to block UV irradiation on perovskite films and to improve the interface contact with perovskite layer as well as decrease the trap states of TiO 2 via chemical bonding by modifying an efficient UV absorber of 2,2′-methylenebis (4-tert-octyl-6-benzotriazole phenol) (UV-360) on the TiO 2 ETLs. Additionally, the triazole groups in UV-360 combine with the uncoordinated cations of perovskite to reduce the defects at TiO 2 /perovskite interface, and a large-grained perovskite film with low grain boundaries is also formed on the UV-360 modified TiO 2 ETLs owing to the reduction of perovskite nucleation sites. As a result, the modification of UV-360 on TiO 2 greatly filtrates the UV attack on perovskite photosensitive layer and suppresses the interfacial charge recombination as well as promotes charge extraction. Finally, the carbon-based CsPbBr 3 PSC tailored wtih UV-360 modified TiO 2 ETLs free of encapsulation achieves a champion PCE up to 9.61% with super-stability under long-term light soaking as well as UV illumination, high temperature and high humidity conditions in air. Our work provides a new perspective to achieve PSCs wih high efficiency and stability by introducing UV-absorption functional materials. [ABSTRACT FROM AUTHOR]

Carbon-based all-inorganic CsPbBr 3 perovskite solar cells (PSCs) have been a promising candidate in the field of photovoltaics due to its simple preparation process and excellent stability in air with high humidity. However, the power conversion efficiency (PCE) of such cells is still unsatisfactory to this day because of the large energy offset and poor hole extraction at the interface of CsPbBr 3 /carbon. Here, a MoO 2 /N-doped carbon nanospheres (NC) composite with high hole mobility and matched energy level is prepared by a facile one-step pyrolysis process and introduced into carbon-based all-inorganic CsPbBr 3 PSC as a hole-transporting material (HTM) to enhance energy level alignment, interface contact and charge extraction as well as to passivate CsPbBr 3 surface defects, realizing the reduction of energy loss and charge recombination. The optimal PSC based on MoO 2 /NC composite without encapsulation achieves a maximum PCE as high as 9.40% in comparison with 6.68% efficiency for the reference device and exhibits an outstanding long-term stability over 800 h in air atmosphere with 80% relative humidity. This work provides an effective approach to build high-performance and stable all-inorganic CsPbBr 3 PSCs by introducing simple synthetic and efficient MoO 2 /NC composite inorganic HTM. Through enhancing energy level alignment and charge extraction as well as reducing surface defects, MoO 2 /N-doped carbon nanospheres composite HTMs help CsPbBr 3 PSC achieve a champion PCE of 9.40% and excellent stability. Image 1 • MoO 2 /NC composite is prepared by a facile one-step pyrolysis process. • The charge extraction at CsPbBr 3 /carbon interface is markedly promoted. • A maximum PCE as high as 9.40% is achieved for device based on MoO 2 /NC composite. • The unencapsulated device shows excellent long-term moisture tolerance over 800 h. [ABSTRACT FROM AUTHOR]

Carbon-based hole-transporting material (HTM)-free CsPbBr 3 perovskite solar cells (PSCs) provide new opportunities for promoting the commercial application of PSCs because of the low cost, simple preparation process and excellent stability under various extreme conditions. One of the remaining problems for inorganic CsPbBr 3 PSCs is the low power conversion efficiency (PCE) due to the large energy level difference and inefficient hole extraction at CsPbBr 3 /carbon interface. Herein, polyaniline/graphite (PANi/G) composites are incorporated into carbon electrode to tailor work function and to improve hole-selectivity of back electrode for enhanced energy level alignment and interfacial hole extraction, leading to a remarkably reduced energy loss and charge recombination. The HTM-free CsPbBr 3 PSC based on carbon-PANi/G electrode achieves a PCE of 8.87%, which is increased by 43.8% in comparison with 6.17% for the control device. Moreover, the unencapsulated device shows excellent long-term moisture tolerance with the initial PCE maintaining 93.5% even exposure to air atmosphere with 80% RH at 25 °C over 50 days. The successful improvement of energy level alignment and charge extraction in device by directly incorporating PANi/G composites into carbon electrode offers a promising strategy in developing low-cost and efficient HTM-free PSCs. By incorporating PANi/G composites into carbon electrode for enhanced energy level alignment and interfacial hole extraction, the unencapsulated HTM-free CsPbBr 3 PSC achieves a champion power conversion efficiency of 8.87% and excellent operational stability. Image 1 • PANi/G composites are incorporated into carbon to promote hole extraction. • The matching WF markedly improves energy level alignment at CsPbBr 3 /carbon interface. • The carbon-based HTM-free CsPbBr 3 PSC achieves a PCE up to 8.87%. • The unencapsulated device shows excellent air-stability over 50 days in 80% RH. [ABSTRACT FROM AUTHOR]

The interaction between solvent molecules and lead halides in precursor solution is important in controlling perovskite film morphology and crystallization process, which determines the photovoltaic performances of solar cells. Herein, we demonstrate two organic solvent molecules, acetonitrile (ACN) and N -methyl-2-pyrrolidone (NMP) with adverse coordinating capacity to Pb2+ center, as precursor additives to control the interaction between dimethyl formamide (DMF) and PbBr 2 and therefore the crystallization process of CsPbBr 3 films. By carefully varying the concentration of additives (ACN and NMP) in DMF solutions, the final perovskite films with markedly enlarged grains are obtained in both scenarios owing to the tuned bonding strength of PbBr 2 -DMF complexes and grain growth dynamics. Upon assembling into all-inorganic CsPbBr 3 perovskite solar cells, the optimized power conversion efficiencies of 9.22% and 9.53% are obtained for ACN- and NMP-containing devices, which are much higher than that of control device with average 7.38%-efficiency. More importantly, the optimal device free of encapsulation exhibits excellent stability under persistent attack at 40 °C and 90% relative humidity over 30 days. The improved perovskite film quality and device performances may pave the way for full-bromine perovskite solar cells in the future. Image 1 • Small molecular ACN and NMP are introduced into the PbBr 2 precursors. • The interactions between PbBr 2 and DMF are regulated by ACN and NMP. • The all-inorganic CsPbBr 3 perovskite film presents large grain size. • The charge recombination is minimized for high-performance inorganic PSCs. [ABSTRACT FROM AUTHOR]

Carbon-based all-inorganic CsPbBr 3 perovskite solar cells (PSCs) have attracted growing interests due to low cost and excellent tolerances toward moisture, temperature, oxygen and ultraviolet light. However, carrier recombination of CsPbBr 3 film and large energy level differences at CsPbBr 3 /carbon interface are still the most crucial problem for further enhancement of power conversion efficiency. In the current study, an intermediate energy level at CsPbBr 3 /carbon interface and CsPbBr 3 film passivation are employed by coating hexane solution of CsPbBr x I 3-x nanocrystals (NCs) on the perovskite layer. Through systematic study on interfacial engineering, it is found that CsPbBr x I 3-x NCs with tunable energy level can remarkably reduce energy loss and hexane under passivation treatment can enlarge perovskite grain size as well as reduce trap state density. A champion power conversion efficiency of 9.45% is achieved for CsPbI 3 NCs tailored all-inorganic CsPbBr 3 PSC in comparison with 5.26% for NCs-free device, with the unencapsulated carbon-based CsPbBr 3 PSC exhibiting remarkable long-term stability over 900 h in 80% relative humidity air atmosphere at 25 °C. This work provides an effective approach to promote charge extraction and reduce defect states density as well as enhance the performance of PSCs. Image 1 • Dual-function interface engineering are developed to promote charge extraction. • High-quality CsPbBr 3 film and the reduced energy loss are realized simultaneously. • CsPbBr 3 PSC tailored with CsPbI 3 NCs achieves a champion PCE of 9.45%. • All-inorganic CsPbBr 3 PSC free of encapsulation exhibits excellent stability. [ABSTRACT FROM AUTHOR]

Inorganic cesium lead bromide (CsPbBr 3) perovskite solar cells (PSCs) have superior moisture- and thermal-stability in comparison with organic-specie or/and I-containing devices. However, the narrow-spectra absorption (<550 nm) arising from their large bandgap of 2.3 eV for CsPbBr 3 halide has markedly limited the further efficiency enhancement of corresponding inorganic device, therefore a great challenge is to broaden the light response range without sacrificing environmental tolerances. In this work, we constructively fabricate a CsPbBr 3 /bulk-heterojunction (organic J 61 -ITIC) photoactive layer to widen the optical absorption range of inorganic CsPbBr 3 based interlayer-free device. Arising from the broadened light response wavelength from 550 to 780 nm and precisely optimized crystal lattice by incorporating Rb+ into CsPbBr 3 film, the optimal device achieves a power conversion efficiency up to 10.34% under one sun illumination. Upon persistent attacks by heat of 80 °C (0% humidity) or 90% humidity (25 °C) over 40 days, the solar cell can still remain approximately 96% of initial efficiency, demonstrating the excellent stability for practical application. Image 1 • Organic bulk-heterojunction photoactive layer is integrated into inorganic CsPbBr 3 PSCs. • Alkalis ion Rb+ has been doped into inorganic CsPbBr 3 perovskite films. • The integrated CsPbBr 3 /bulk-heterojunction solar cell achieves a PCE of 10.34%. • The optimal device shows excellent long-term stability. [ABSTRACT FROM AUTHOR]

• Divalent transition metal ions are doped into the lattices of CsPbBr 3 perovskite. • The enlarged grain size and decreased energy differences reduce charge recombination. • The all-inorganic CsPbBr 3 PSC free of HTLs achieves a PCE up to 9.18%. • The optimal device shows excellent long-term stability over 760 h in 80% RH. The perovskite film with large grain size and low defect states density is technically important to improve the power conversion efficiency and environmental stability of perovskite solar cells (PSCs). In the present work, we raise a compositional engineering strategy of inorganic CsPbBr 3 perovskite films by substituting partial Pb2+ with divalent transition metal ions having smaller ionic radius (TM2+ = Mn2+, Ni2+, Cu2+ and Zn2+). The photovoltaic performances of hole transporting layer-free all-inorganic CsPbBr 3 PSCs are markedly improved through maximizing grain size with few grain boundaries as well as low trap states density and minimizing energy loss in charge carrier transfer. A champion power conversion efficiency as high as 9.18% is achieved for the all-inorganic CsPb 0.995 Zn 0.005 Br 3 PSC free of encapsulation, which shows a remarkable long-term stability over 760 h in 80% humidity air atmosphere at 25 °C. The high efficiency and improved stability demonstrate compositional engineering is a promising strategy to forward high-quality perovskite films and high-performance of all-inorganic CsPbBr 3 PSCs. [ABSTRACT FROM AUTHOR]

All‐inorganic cesium lead bromide (CsPbBr3) perovskite solar cells have attracted enormous attention owing to their outstanding stability in comparison with organic–inorganic hybrid devices. The greatest weakness for inorganic CsPbBr3 solar cells is their lower power conversion efficiencies, mainly arising from inferior light‐absorbance range and serious charge recombination at interfaces or within perovskite films. To address this issue, the lattice doping of lanthanide ions (Ln3+ = La3+, Ce3+, Nd3+, Sm3+, Eu3+, Gd3+, Tb3+, Ho3+, Er3+, Yb3+, and Lu3+) into CsPbBr3 films for all‐inorganic solar cells free of hole‐transporting materials and precious metal electrodes is presented. Arising from the enlarged grain size and prolonged carrier lifetimes upon incorporating Ln3+ ions into perovskite lattice, the performances of these inorganic CsPbBr3 solar cell devices are significantly enhanced, achieving a champion efficiency as high as 10.14% and an ultrahigh open‐circuit voltage of 1.594 V under one sun illumination. Meanwhile, the nearly unchanged efficiency upon persistent attack by 80% RH in air atmosphere over 110 d and enhanced thermal stability at 80 °C over 60 d provide new opportunities of promoting commercialization of all‐inorganic CsPbBr3 perovskite solar cells. Lanthanide ions are doped into CsPbBr3 films to modulate crystal lattice for high‐performance all‐inorganic perovskite solar cells. Arising from the improved grain size and carrier lifetime, the solar cell achieves a champion power conversion efficiency of 10.14%, an ultrahigh Voc of 1.594 V, and excellent stability. [ABSTRACT FROM AUTHOR]