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A novel concept based on the use of solutions containing already qualified crystalline antimony-doped tin oxide SnO:Sb (ATO) nanoparticles has been developed. ATO nanoparticles are decorated by reduced graphene oxide (rGO) through a hydrothermal synthesis method. The electrical and optical properties of the graphene oxide films are investigated systematically. The sheet resistance ( R) of the ATO-rGO films decreases with the increase in the rGO content in the precursor solution. The R can be decreased after the ATO-rGO films annealing in the air for 1 h and can be further decreased by depositing Au on the surface of the films. The optimum property of the ATO-rGO film shows that the R is 80 Ω/□ and the transmittance is about 70 %. The ATO-rGO films are used as the anode of the organic solar cells. The anode film impact on the performance of the devices is studied. Finally, the power conversion efficiency (PCE) of the device based on the poly-(3-hexylthiophene): [6, 6]-phenyl C61-butyric acid methyl ester (PCBM) blended is 1.85 %, and the PCE of the device based on the poly-benzo[1,2-b:4,5-b′] dithio-phene thieno[3,4-b] thiophene:PCBM blended is 3.4 %. [ABSTRACT FROM AUTHOR]

In this article, we in situ fabricated copper sulfide (CuS) on fluorinated tin oxide (FTO) substrate using a low temperature and low cost hydrothermal method and then organic solar cells (OSCs) were fabricated by using a thin layer of CuS film as hole transporting layer (HTL). Our CuS films, consisting of two-dimensional (2D) intersected hexagonal nanosheets, are stoichiometric and show p-type electrical conductivity, a good transparency and a high hole mobility. The Fermi level, valence and conduction band energies for CuS HTL are characterized in detail through photoelectron spectroscopy studies. The small energy barrier between the valance band of CuS and the HOMO of poly(3-hexylthiophene) (P3HT) and the high hole mobility and electrical conductivity of CuS nanosheet film benefit for the hole transporting. Therefore, CuS HTL to OSCs results in a power conversion efficiency of 3.4% with P3HT and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as the active layer, which is a 13.3% increase in performance than devices with a poly (3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) HTL. Therefore, low-cost, environmental friendly and stable CuS is an appropriate choice for hole transporting materials (HTMs) in OSCs. [ABSTRACT FROM AUTHOR]

Mixed tin–lead (Sn–Pb) perovskites often face a daunting challenge: rapid and uncontrollable crystallization, leading to a plethora of defects and significant stress. This issue is particularly exacerbated during the blade‐coating preparation of scalable Sn–Pb perovskite films. In this study, a facile strategy involving the addition of ammonium citrate (AC) to narrow‐bandgap mixed Sn–Pb perovskite precursors is introduced. AC, armed with its arsenal of multiple carboxyl and amino groups, acts as a virtuoso conductor, orchestrating controlled crystal growth by harmonizing with Pb2+ and Sn2+ ions. This addition significantly boosts the crystallinity of the perovskite films, alleviates interface stress, inhibits Sn2+ oxidation, and mitigates interfacial defects. Consequently, The blade‐coated AC‐incorporated mixed Sn–Pb perovskite solar cells achieve a high photovoltaic conversion efficiency of nearly 21%. Furthermore, extending this strategy to two‐terminal all‐perovskite tandem solar cells yielded a remarkable maximum efficiency of 27.20%. This work presents an effective strategy for producing efficient blade‐coated mixed Sn–Pb perovskite solar cells, heralding a pathway toward scalable fabrication of all‐perovskite tandem solar cells. [ABSTRACT FROM AUTHOR]

Despite advances in mixed tin‐lead (Sn‐Pb) perovskite‐based solar cells, achieving both high‐efficiency and long‐term device stability remains a major challenge. Current device deficiencies stem partly from inefficient carrier transport, originating from defects and improper band energy alignment among the device's interfaces. Developing multifunctional interlayer materials simultaneously addressing the above concerns poses an excellent strategy. Herein, through molecular and crystal engineering, an amine‐functionalized C60 mono‐adduct derivative (C60‐2NH3 = bis(2‐aminoethyl) malonate‐C60) is utilized for the synthesis of the first crystalline fullerene‐based 2D metal halide semiconductor, namely (C60‐2NH3)Pb2I6. Single crystal XRD studies elucidated the structure of the new material, while DFT calculations highlighted the strong contribution of C60‐2NH3 to the electronic density of states of the conduction band of (C60‐2NH3)Pb2I6. Utilization of C60‐2NH3 as an interlayer between a FA0.6MA0.4Pb0.7Sn0.3I3 perovskite and a C60 layer offered superior band energy alignment, reduced nonradiative recombination, and enhanced carrier mobility. The corresponding perovskite solar cell (PSC) device achieved a power conversion efficiency (PCE) value of 21.64%, maintaining 90% of its initial efficiency, after being stored under a N2 atmosphere for 2400 h. This work sets the foundation for developing a new family of functional materials, namely Fullerene Metal Halide Semiconductors, targeting applications from photovoltaics to catalysis, transistors, and supercapacitors. [ABSTRACT FROM AUTHOR]

Owing to their remarkable and adjustable optoelectronic properties, halide perovskites (HPs) have been regarded as a class of promising materials for various optoelectronic applications based on different energy conversion reactions, including photovoltaic cell, photocatalysis, electrocatalysis, and photoelectrochemical (PEC) systems. However, the low stability of HPs upon exposure to ambient conditions (e.g., water, heat, light, electricity) greatly hinders the practical applications of HPs. In the past few years, significant efforts have been devoted to enhancing the eventual stability of the perovskite‐based optoelectronic systems, mainly focusing on delivering improvements in the stabilities of halide perovskite materials and the relevant operation conditions of optoelectronic systems, which deserve in‐depth and systematic summaries. In this comprehensive review, the in‐depth environment‐induced decomposition mechanisms of typical HPs are elucidated. Simultaneously, the strategies for addressing the instability issues of halide perovskite materials are critically reviewed, including dimension control, compositional engineering, ligand passivation, and encapsulation engineering. Furthermore, the photoelectric applications based on the modified HPs and operation conditions are discussed systematically. In the last part of this review, future perspectives and outlooks toward the stability of HPs and their photoelectric applications are envisaged respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] Despite their excellent environmental stability, low defect density, and high carrier mobility, large- n quasi-two-dimensional halide perovskites (quasi-2DHPs) feature a limited application scope because of the formation of self-assembled multiple quantum wells (QWs) due to the similar thermal stabilities of large- n phases. However, large- n quasi-phase-pure 2DHPs (quasi-PP-2DHPs) can solve this problem perfectly. This review discusses the structures, formation mechanisms, and photoelectronic and physical properties of quasi-PP-2DHPs, summarises the corresponding single crystals, thin films, and heterojunction preparation methods, and presents the related advances. Moreover, we focus on applications of large- n quasi-PP-2DHPs in solar cells, photodetectors, lasers, light-emitting diodes, and field-effect transistors, discuss the challenges and prospects of these emerging photoelectronic materials, and review the potential technological developments in this area. [ABSTRACT FROM AUTHOR]

Weak‐light imaging holds immense significance in various imaging applications. Recently, there has been significant research focused on 2D perovskites for photodetectors (PDs), owing to their superior photoelectric properties. However, the utilization of 2D perovskites for high‐performance weak‐light detection remains limited, and there is a notable absence of demonstration in weak‐light ultraviolet (UV) imaging. Herein, a high‐sensitive UV detectors with an ultra‐low detection limit for weak‐light imaging are demonstrated, utilizing 2D perovskite (PA)2PbBr4 (PPB) single crystals (SCs). Leveraging the exceptional quality of SCs, the PPB‐based PD exhibits outstanding operational performances, including a low dark current of 0.735 pA, high on/off ratio of 4150 under 263.3 mW cm−2 illimitation, and extensive linear dynamic range of 153.61 dB, which is currently the highest reported value among 2D perovskite SC detectors. Notably, PPB PDs demonstrate a remarkable response under 5.49 nW cm−2 illumination, enabling it to exhibit outstanding photo‐response with an excellent detectivity of 2.3 × 1013 Jones and responsivity of 2.22 A W−1. Importantly, high‐resolution images are successfully obtained under weak‐light illumination. These findings underscore the immense potential of 2D perovskite for UV weak‐light imaging. [ABSTRACT FROM AUTHOR]

Perovskite single crystals (SCs) have gained significant interest in various applications owing to their superior optoelectrical and physical characteristics as compared to polycrystalline films. However, a considerable portion of incident light is typically reflected at the surface of perovskite SCs, leading to insufficient light absorption within the crystal bulk, ultimately resulting in reduced performance of SC‐based photodetectors. In the present work, an inverted pyramid‐shaped structure is in situ introduced on the surface of an MAPbBr3 SC during the crystal growth process, which can reduce light reflection in the surface region and enhance light absorption of the SC. Additionally, the hydrophobic small molecule copper (II) phthalocyanine (CuPc) is thermally evaporated onto the SC, forming a CuPc/MAPbBr3 heterojunction for the first time. The CuPc/pyramid‐shaped MAPbBr3 heterojunction‐based photodetector exhibits self‐powered characteristics and superior optoelectrical performance, achieving a photocurrent of greater than 10−5 A (10−7 A), a responsiveness of 257 mA W−1 (8.84 mA W−1), and a detection rate of 2.98 × 1012 Jones (1.02 × 1011 Jones) at −2 V (0 V) bias. Simultaneously, the device demonstrates excellent long‐term stability under high humidity conditions, retaining 90.5% of its initial photocurrent even after 60 days in a 60–80% humidity environment. [ABSTRACT FROM AUTHOR]

Wide‐bandgap (WBG) perovskite solar cells (PSCs) have garnered significant attention for their potential applications in tandem solar cells. However, their large open‐circuit voltage (VOC) deficit and serious photo‐induced halide segregation remain the main challenges that impede their applications. Herein, a post‐treatment strategy without thermal annealing is presented to form a 2D top layer of 2‐thiopheneethylammonium lead halide (n = 1) on WBG perovskites. This thermal annealing‐free post‐treatment method can more effectively passivate the defects of WBG methylamine (MA)‐free formamidinium/cesium lead iodide/bromide perovskite films and suppress photo‐induced perovskite phase segregation, as compared with the thermal annealing method that yields multi‐2D phases. The resulting opaque and semi‐transparent 1.66 eV‐bandgap perovskite solar cells deliver maximum power conversion efficiencies of 21.47% (a small VOC deficit of 0.43 V) and 19.11%, respectively, both of which are among the highest reports for inverted MA‐free WBG PSCs. Consequently, four‐terminal all‐perovskite tandem cells realize a remarkable efficiency of 26.64%, showing great promise for their applications in efficient multi‐junction tandem solar cells. [ABSTRACT FROM AUTHOR]

[Display omitted] Metal halide perovskites films have attracted great interest because of their solution-proceed fabrication and potential applications for next-generation displays. However, their non-ideal photoluminescence quantum efficiency (PLQE) and stability still does not meet the requirements of displays. Here, we adopt lanthanum ion (La3+) doping strategy to enhance its luminescence performance and the possibility of taking it to commercialization. In addition to the entry of lanthanum ions into the lattice to greatly improve the crystal quality, the excess La3+ gives rise to the formation of newly developed formamidinium cesium lanthanum bromine, (FA, Cs) 2 LaBr 5 , which provides additional energy transport pathways, therefore concentrating more energy onto the perovskite host. Consequently, a near-unity PLQE of 99.5% is realized in standardized green-emission cesium (Cs)/formamidinium (FA) mixed FA 0.7 Cs 0.3 PbBr 3 perovskite films. The introduction of La3+ can also lead to markedly stability with nearly 1000 days' shelf storage half-lifetime and 400 hours' light-irradiation T 90 lifetime as well as much-enhanced color purity. Moreover, the films with La3+ doping enable full-visible spectral enhancement and high-performance white light emission and trichromatic luminescence with 98.9% coverage of the color gamut area required for the Rec. 2020 standard, which suggest that perovskite films have great application potential for backlights in liquid crystal display technologies. [ABSTRACT FROM AUTHOR]

Highlights: A versatile material-antimony potassium tartrate is added to wide-bandgap perovskite cells for the first time. Inverted wide-bandgap perovskite solar cells with a structure of ITO/MeO-2PACz/perovskite/C60/ALD-SnO2/Cu yield a champion power conversion efficiency of 20.35%. A perovskite/perovskite four-terminal tandem solar cell with efficiency of 26.3% is achieved. Wide-bandgap (WBG) perovskites have been attracting much attention because of their immense potential as a front light-absorber for tandem solar cells. However, WBG perovskite solar cells (PSCs) generally exhibit undesired large open-circuit voltage (VOC) loss due to light-induced phase segregation and severe non-radiative recombination loss. Herein, antimony potassium tartrate (APTA) is added to perovskite precursor as a multifunctional additive that not only coordinates with unbonded lead but also inhibits the migration of halogen in perovskite, which results in suppressed non-radiative recombination, inhibited phase segregation and better band energy alignment. Therefore, a APTA auxiliary WBG PSC with a champion photoelectric conversion efficiency of 20.35% and less hysteresis is presented. They maintain 80% of their initial efficiencies under 100 mW cm−2 white light illumination in nitrogen after 1,000 h. Furthermore, by combining a semi-transparent WBG perovskite front cell with a narrow-bandgap tin–lead PSC, a perovskite/perovskite four-terminal tandem solar cell with an efficiency over 26% is achieved. Our work provides a feasible approach for the fabrication of efficient tandem solar cells. [ABSTRACT FROM AUTHOR]

Antimony selenosulfide (Sb2(S,Se)3) has been emerging as a promising light absorber in the past few years owing to tunable bandgap (1.1–1.7 eV), high absorption coefficient (>105 cm−1) and excellent phase and environmental stability. However, the efficiency of Sb2(S,Se)3 solar cells lags far behind the Shockley–Queisser limit. One of the critical obstacles originates from various extrinsic and intrinsic defects. They mostly locate in the deep energy levels and are prone to form recombination centers, inhibiting the improvement of device performance. Herein, surface post‐treatment via potassium iodide is introduced to fabricate high‐quality Sb2(S,Se)3 films and solar cells. The surface post‐treatment not only manipulates the crystal growth process to form compact films with larger grain size but also forms better band alignment and inhibits the formation of deep‐level defects antimony antisite (SbSe), thus improving the quality of heterojunction. Consequently, the resultant Sb2(S,Se)3 solar cells achieve a champion power conversion efficiency of 9.22%. This study provides a new strategy of passivating deep‐level intrinsic defects via surface post‐treatment for high‐efficiency Sb2(S,Se)3 solar cells. [ABSTRACT FROM AUTHOR]

Highlights: Through materials analysis and theoretical calculations, the defects of CsSnI3 nanowires (NWs) were effectively passivated via incorporating 1-butyl-2,3-dimethylimidazolium chloride into perovskites. The high-performance CsSnI3 NW photodetectors (PDs) were achieved with a responsivity of up to 0.237 A W−1, a high detectivity of 1.18 × 1012 Jones and a linear dynamic range of 180 dB. These values are comparable to the reported high-performance Pb-based perovskite PDs and higher than those of the Pb-free perovskite PDs. Our unpackaged devices exhibit ultra-high stability with no degradation after 60 days of storage in air (25 °C, 50% humidity). In recent years, Pb-free CsSnI3 perovskite materials with excellent photoelectric properties as well as low toxicity are attracting much attention in photoelectric devices. However, deep level defects in CsSnI3, such as high density of tin vacancies, structural deformation of SnI6− octahedra and oxidation of Sn2+ states, are the major challenge to achieve high-performance CsSnI3-based photoelectric devices with good stability. In this work, defect passivation method is adopted to solve the above issues, and the ultra-stable and high-performance CsSnI3 nanowires (NWs) photodetectors (PDs) are fabricated via incorporating 1-butyl-2,3-dimethylimidazolium chloride salt (BMIMCl) into perovskites. Through materials analysis and theoretical calculations, BMIM+ ions can effectively passivate the Sn-related defects and reduce the dark current of CsSnI3 NW PDs. To further reduce the dark current of the devices, the polymethyl methacrylate is introduced, and finally, the dual passivated CsSnI3 NWPDs show ultra-high performance with an ultra-low dark current of 2 × 10–11 A, a responsivity of up to 0.237 A W−1, a high detectivity of 1.18 × 1012 Jones and a linear dynamic range of 180 dB. Furthermore, the unpackaged devices exhibit ultra-high stability in device performance after 60 days of storage in air (25 °C, 50% humidity), with the device performance remaining above 90%. [ABSTRACT FROM AUTHOR]

Despite extensive study, the bandgap characteristics of lead halide perovskites are not well understood. Usually, these materials are considered as direct bandgap semiconductors, while their photoluminescence quantum yield (PLQY) is very low in the solid state or single crystal (SC) state. Some researchers have noted a weak indirect bandgap below the direct bandgap transition in these perovskites. Herein, application of pressure to a CsPbBr3 SC and first‐principles calculations reveal that the nature of the bandgap becomes more direct at a relatively low pressure due to decreased dynamic Rashba splitting. This effect results in a dramatic PLQY improvement, improved more than 90 times, which overturns the traditional concept that the PLQY of lead halide perovskite SC cannot exceed 10%. Application of higher pressure transformed the CsPbBr3 SC into a pure indirect bandgap phase, which can be maintained at near‐ambient pressure. It is thus proved that lead halide perovskites can induce a phase transition between direct and indirect bandgaps. In addition, distinct piezochromism is observed for a perovskite SC for the first time. This work provides a novel framework to understand the optoelectronic properties of these important materials. [ABSTRACT FROM AUTHOR]

This article, published in Advanced Energy Materials, discusses a new synthetic strategy for the development of a family of crystalline fullerene metal halide semiconductors. These semiconductors were used to create highly efficient and stable perovskite solar cells. The study highlights the potential for fully customizable fullerene-based materials for applications beyond photovoltaics. The authors of the article include Wenwen Zheng, Ioannis Spanopoulos, and several other researchers. [Extracted from the article]

• Time-resolved microwave conductivity (TRMC) was employed to assess charge carrier mobilities and recombination rate constants in perovskite films. The findings reveal that the post-treatment strategy enhances film quality, improves carrier mobility, and reduces non-radiative recombination. • We fabricate inverted WBG PSCs with a structure of ITO/MeO-2PACz/perovskite/C60/ALD-SnO 2 /Cu. These PSCs yields a champion PCE of 21.48% with negligible hysteresis. • A perovskite/perovskite four-terminal tandem solar cell with efficiency of 28.07% is achieved. This is one of the highest efficiencies reported for all-perovskite tandem solar cells. As an essential light-absorbing material in perovskite-based tandem solar cells, wide-bandgap (WBG) perovskite has garnered extensive attention. Nevertheless, due to severe non-radiative recombination from tail states, as well as photoinduced phase segregation and unoptimized charge transfer, WBG perovskite solar cells (PSCs) typically display significant open-circuit voltage (V OC) loss and low fill factor (FF). In this work, we report to modify the 1.68 eV WBG perovskite film upon optimized surface passivation with 1,3-propane-diammonium iodide (PDAI 2). Time-resolved microwave conductivity measurement is employed to analyze the tail states, mobilities of charge carriers and the rate constants of recombination in perovskite films. The results indicate that the optimized surface modification strategy not only enhances film quality, boosts carrier transport, but also suppresses tail states and therefore diminishes non-radiative recombination, consequently elevating the V OC and FF of the device. Hence, the PDAI 2 -assisted WBG PSCs deliver an optimal efficiency of 21.48 %, accompanied by a V OC of 1.243 V. Furthermore, the integration of a narrow-bandgap tin–lead PSC with a semi-transparent WBG PSC results in a four-terminal perovskite/perovskite tandem solar cell, showcasing an efficiency surpassing 28 %. Our research offers a practical approach for producing efficient WBG PSCs and tandem solar cells. [ABSTRACT FROM AUTHOR]

Quasi‐two‐dimensional (quasi‐2D) perovskite light‐emitting diodes (PeLEDs) are considered as one of the most potential candidates in electroluminescence territory owing to their unique quantum confinement effect and excellent thermal stability of the light. Nevertheless, heterogeneous energy domain distribution leads to severe non‐radiative recombination in the process of energy transfer, which enormously hinders the performance and application of PeLEDs. Herein, an ambipolar amino acid, 5‐aminovaleric acid (5AVA), is demonstrated to be able to coordinate lead and halides simultaneously with its carboxyl and amidogen groups. The coordinated ambipolar molecule not only reconstitutes energy domains of perovskites but also minimizes the interfacial defects of PeLEDs. Accordingly, the presence of 5AVA in perovskite precursors leads to dramatic suppression of the n = 1 and n = 2 phases and accelerates energy transfer from wide bandgap domains to narrow bandgap ones. As a result, maximum external quantum efficiency (EQE) of 19.3% (18.20% ± 1.10%) is achieved in quasi‐2D green PeLEDs with current efficiency of 61.7 cd A−1. [ABSTRACT FROM AUTHOR]

External encapsulation technique as a straightforward craft process has been adopted to prevent the infiltration of moisture and oxygen, thereby improving environmental stabilities of lead halide perovskite solar cells (PSCs). However, irreversible light‐induced degradation originating from various vacancies and ion diffusion or migration inside the device cannot be efficiently solved by external encapsulation. Herein, an internal encapsulation strategy by introducing NbCl5 at the buried tin oxide/perovskite interface and spin‐casting n‐butylammonium bromide on top of perovskite is developed to comprehensively passivate the vacancies and hence block the channels for ion diffusion or migration. The internal encapsulation strategy results in better homogeneous electron transport layer and effective vacancy passivation at the buried interface and simultaneously generates a more homogeneous, better crystallized perovskite in the vertical direction with significantly reduced residual PbI2. Furthermore, fewer oxygen vacancies and formation of ultrathin Nb2O5 lead to a better interfacial energy level alignment for electron transfer. As a result, power conversion efficiency (PCE) of the resulting PSCs is as high as 24.01%. More importantly, the device demonstrates an excellent stability, retaining 88% of its initial PCE at its maximum power point tracking measurement (under 100 mW cm–2 white light illumination at ≈55 °C temperature, in N2 atmosphere) after 1000 h. [ABSTRACT FROM AUTHOR]

All-inorganic Bi-based perovskites have attracted much attention due to their excellent stability, environmentally friendly, and low-cost solution processability. However, due to the large exciton binding energy and small light absorption coefficient, the performance of the Bi-based perovskite photodetector (PD) is far behind of the traditional Pb-based perovskite PDs. In this work, the lead-free all-inorganic Cs3Bi2I9 (CBI) perovskite single crystal was synthesized by a space-confined antisolvent-assisted crystallization method for high-performance, semi-transparent, and self-driven PDs with an ITO/SnO2/CBI/PTAA/Au/ITO structure. Electrical and optical properties of Au/ITO transparent electrode were studied considering its figure of merit and device quantum efficiency through optimizing the Au thickness. Finally, our optimized semi-transparent device showed excellent self-driven performance with a large on/off ratio of ∼5700, a high responsivity of 52.06 mA/W, a high detectivity of >1012 Jones, and a large linear dynamic range of up to 140.7 dB. In addition, our device demonstrated excellent characteristics to the weak light detection and the long-term stability. The Au/ITO electrode was adopted and tailored to balance the device performance and transparency, which provides a good route for developing high-performance and transparent devices in the future. [ABSTRACT FROM AUTHOR]

P‐type semiconductor cuprous oxide (Cu2O) offers promising optoelectronic applications such as solar cells and photodetectors owing to its considerable absorption coefficients and high carrier mobility. However, polycrystalline Cu2O films with low carrier mobility resulting from excessive grain boundaries and structure disorder fail to meet the demands for these optoelectronic applications. Here a stress‐assisted thermal oxidation method to fabricate p‐type <110>‐textured quasi‐single crystalline Cu2O (c‐Cu2O) wafers with centimeter‐scale grains is developed. It is found that strain energy induced by thermal contact stress plays a critical role in crystal growth. The resultant <110>‐textured quasi‐single c‐Cu2O wafers exhibit excellent crystallinity with rocking curve having a low full width at half maximum of 0.022°, a low defect density of 2 × 1011 cm−3, a high mobility exceeding 100 cm2 V−1 s−1, and a long minority lifetime of 98.5 µs. Such quasi‐single c‐Cu2O wafers lead to efficient solar cells with an open‐circuit voltage of 0.95 V and highly responsive photodetectors with superior cycling stability. These results indicate not only the advancement of fabricating high‐quality Cu2O wafers upon controllable methodology but also the promising optoelectronic applications using p‐type metal oxide semiconductors. [ABSTRACT FROM AUTHOR]

SnO2 compact layer (c‐SnO2) frequently suffers from degradation in high temperature processes (HTP) such as crack, worse interfacial contact, and electrical properties, that is, annealing effect. To solve this problem, a kind of bifunctional SnO2 colloid is developed by using small molecular oxalate whose organic components can be removed clearly at a low temperature process (LTP). The c‐SnO2 and SnO2 mesoporous layer (m‐SnO2) derived from the fresh and aged sols with the same colloid show no annealing effect, decreasing oxygen vacancy, and adsorbing water on increasing annealing temperature. The champion devices of LTP and HTP SnO2 planar perovskite solar cells (PSCs) achieve, respectively, stabilized photoelectric conversion efficiencies (PCEs) of 20.74% and 20.70%. In contrast, the performance of champion devices of their mesoporous counterparts is significantly improved, showing nearly hysteresis free character with stabilized PCEs of 22.40% and 22.37%, respectively. The inclusion of m‐SnO2 plays a role of an energy bridge, improving electrons collection efficiency, which is supported by photoluminescence and transient photoluminescence characterizations. HTP SnO2 mesoporous PSCs can preserve 97.6% and 80% of their initial PCEs after aging for 25 weeks and 8‐h irradiated/16‐h dark cycle within 104 h. The high stability of HTP SnO2 PSCs may ascribe to low oxygen vacancy and adsorbed water of HTP SnO2. [ABSTRACT FROM AUTHOR]

Metal halide perovskite nanocrystals (NCs) serve as a kind of ideal semiconductor for luminescence and display applications. However, the optoelectronic performance and stability of perovskite NCs are mainly subjected to current ligand strategies since these ligands exhibit a highly dynamic binding state, which complicates NC purification and storage. Herein, a method named diffusion‐induced extraction is developed for crystallization (DEC) at room temperature, in which silicone oil serves as a medium to separate the solvent from perovskite precursors and diethyl ether promotes the nucleation, leading to highly emissive perovskite NCs. The formation mechanism of NCs using this approach is elucidated, and their optoelectronic properties are fully characterized. The resultant NCs ink exhibits a high photoluminescence quantum yield (PLQY) over 90% with a narrow full width at half maximum of 17 nm. The DEC method strengthens the interaction between ligand and NCs via the hydrophobic silicone oil. Therefore, the NCs maintain almost 95% of their initial PLQYs after aging more than seven months in air. The findings will be of great significance for the continued advancement of high PLQY perovskite NCs through a better understanding of formation dynamics. The DEC strategy presents a major step forward for advancing the field of perovskite semiconductor nanomaterials. [ABSTRACT FROM AUTHOR]

• Molecular weight has a significant effect on the mobility and electrical conductivity of the PTPD. • The interfacial charge transferring and transport between the perovskite and PTPD varies with the PTPD' molecular weight. • We fabricate the inverted PSCs based on MAPbI 3 with a champion PCE of 19.24% with negligible hysteresis. Inverted planar perovskite solar cells (PSCs) with poly(N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine) (PTPD) layer as hole-transporting layer (HTL) exhibit high power conversion efficiencies (PCEs) over 20%. However, the influence of PTPD's molecular weight (Mw) on the performance of PSCs has not been reported yet. Herein, we employ PTPD with various molecular weights as HTL to fabricate highly efficient inverted planar PSCs. Our results show that PTPD with 75 kDa possesses superior conductivity, which can quicken the charge carrier extraction from perovskite to HTL. In addition, the MAPbI 3 perovskite film atop the 75-kDa PTPD is smoother with higher crystallinity and lower defect density. As a result, inverted planar PSCs with 75-kDa PTPD as HTL deliver a highest PCE of 19.24%. Our work provides a beneficial reference for future preparation of stable and highly efficient inverted PSCs with polymer HTL. [ABSTRACT FROM AUTHOR]

Wide bandgap SnO2 usually shows n-type conductivity due to intrinsic defects. Herein, we demonstrate the achievement of p-type conduction in SnO2 with a two-step process, in which 3.3 at. % Mg-doped SnO2 epitaxial films were first grown on c-Al2O3 by pulsed laser deposition and then annealed in an oxygen atmosphere at proper temperature and time. An activation energy of around 85 meV revealed by temperature-dependent resistance measurements verifies Mg as a shallow acceptor in the p-type doping of SnO2. The post-annealing treatment at suitable temperature and time was found to be crucial to greatly enhance the p-type conductivity of Mg-SnO2 by removing the interstitial Mg while maintaining the substitutional Mg in the SnO2 lattice. A hole concentration of 1.43 × 1017 cm−3 and a hole mobility of 4 cm2 V−1 s−1 as determined by Hall-effect measurements were achieved for a sample annealed at optimized conditions of 600 °C and 0.5 h. The achievement of high-quality p-type Mg-SnO2 epitaxial films demonstrates high potential in developing advanced optoelectronic devices based on p-n junctions of SnO2. [ABSTRACT FROM AUTHOR]

Antireflection (AR) film is a widely used technology to enhance the performance of photovoltaic devices that require transparent electrodes in the photovoltaic industry. At present, several AR films including monolayer MgF2 or multilayered composite films, textured polydimethylsiloxane (PDMS) and porous SiO2 have been successfully applied due to their excellent properties. Nevertheless, all of the above-mentioned AR films have some minor drawbacks to overcome, for instance, the cost or thermal durability. Herein, we report a cost-effective and low-temperature method to fabricate a mesoporous aluminum oxide (meso-Al2O3) layer as the AR coating with high thermal durability, which will meet the fabrication condition of various photovoltaic devices. Briefly, the process begins at magnetron sputtering a compact Al2O3 film, which shows no AR effect, followed by a hot water treatment at 80 °C to turn the compact film into a mesoporous film with graded-index and AR effect. The application of meso-Al2O3 AR film enhances the maximum transmittance of our laboratory-used fluorine-doped tin oxide (FTO) from 84% to 89%, which is in good agreement with our theoretical simulation named graded-index approximation. Taking perovskite solar cells (PSCs) as an example, planar PSCs with meso-Al2O3 AR film deliver excellent photon conversion efficiency of 21.5%, which is higher than that of cells without meso-Al2O3 AR film (20.9%). [ABSTRACT FROM AUTHOR]

The plasmonic characteristic of core–shell nanomaterials can effectively improve exciton‐generation/dissociation and carrier‐transfer/collection. In this work, a new strategy based on core–shell Au@CdS nanospheres is introduced to passivate perovskite grain boundaries (GBs) and the perovskite/hole transport layer interface via an antisolvent process. These core–shell Au@CdS nanoparticles can trigger heterogeneous nucleation of the perovskite precursor for high‐quality perovskite films through the formation of the intermediate Au@CdS–PbI2 adduct, which can lower the valence band maximum of the 2,2,7,7‐tetrakis(N,N‐di‐p‐methoxyphenyl‐amine)9,9‐spirobifluorene (Spiro‐OMeTAD) for a more favorable energy alignment with the perovskite material. With the help of the localized surface plasmon resonance effect of Au@CdS, holes can easily overcome the barrier at the perovskite/Spiro‐OMeTAD interface (or GBs) through the bridge of the intermediate Au@CdS–PbI2, avoiding the carrier accumulation, and suppress the carrier trap recombination at the Spiro‐OMeTAD/perovskite interface. Consequently, the Au@CdS‐based perovskite solar cell device achieves a high efficiency of over 21%, with excellent stability of ≈90% retention of initial power conversion efficiencies after 45 days storage in dry air. [ABSTRACT FROM AUTHOR]

Ni 2 P nanosheets were fabricated on carbon fiber using the hydrothermal method and subsequent phosphatization process. The highly conductive Ni 2 P nanosheet arrays could not only facilitate electron transport but also shorten the ion diffusion path. The in-situ grown Ni 2 P nanosheet arrays could be applied as the cathode in Zn battery without any additives and binder. The Ni 2 P//Zn battery based on Ni 2 P nanosheet arrays and metal Zn electrode exhibits excellent electrochemical performance, such as high operating voltage (1.78 V), specific capacity of 231 mAh g−1, and energy density of 318 Wh Kg−1. In addition, the Ni 2 P//Zn battery can maintain a specific capacity retention ~ 80% after 1500 continuous cycles. In view of the excellent electrochemical properties of Ni 2 P//Zn battery, the Ni 2 P will be a potential material for next-generation energy storage devices. • Ni 2 P nanosheet arrays are synthesized on carbon fiber by a two-step procedure. • The Ni 2 P electrode exhibits high specific capacity and good cyclic performance. • A novel Ni 2 P//Zn battery with Zn on carbon fiber as anode was assembled successfully. • The battery with high operating potential shows an energy density of 318 Wh kg−1. [ABSTRACT FROM AUTHOR]

ZnO thin films have been prepared by atomic layer deposition for ultraviolet photodetection with metal-semiconductor-metal (MSM) structure. The innovation of rapid thermal annealing treatment can modulate the carrier concentration of the ZnO thin films, a lowest carrier concentration of 4.4 × 1014 cm−3 was obtained after annealing at 450 °C, resulting in the minimum dark current of 4.5 × 10−8 A at 5 V. Furthermore, these photodetectors demonstrated respectable responsivity of up to 27 A/W, and the detectivity was enhanced to a fairly high value of 8.5 × 1013 Hz1/2/W together with an extremely rapid response of <80 μs. These performance metrics are far superior compared with the records in the existing literature based on ZnO thin films, and are even on a par with nano-structural ZnO devices, while remain the key features of thin film devices, including high reproducibility and facile preparation. • ALD provides thickness control and uniformity. • Annealing can removes defects. • Response time of < 80 µs, respectively. [ABSTRACT FROM AUTHOR]

Abstract The use of aligned one-dimensional nanostructures as scaffolds in organic-inorganic hybrid perovskite photodetectors (PDs) has attracted significant attention due to their large surface area-to-volume ratio and efficient electron transport capability in the radial direction. Here, we report CH 3 NH 3 PbI 3 (MAPbI 3) perovskite photodetectors (PDs) with Ga-doped ZnO nanorods (GZO NRs), prepared by the water bath method, as a scaffold-structure electron transport layer (ETL). Our MoO 3 hole transport layer (HTL) based perovskite PDs using GZO NRs as a scaffold showed a larger light/dark current (I ph / I dark) ratio, higher responsivity and detectivity than those of the undoped ZnO NRs/MAPbI 3 devices at zero bias. These enhancements are attributed to the incorporation of Ga atoms into the ZnO NRs, which reduce the density defect states of ZnO NRs and improves the performance of MAPbI 3 perovskite PDs. In addition, by taking advantage of the GZO NRs scaffold structure, a HTL-free perovskite PD was prepared by using graphite electrodes. The graphite-connected device shows self-powered PD performances with an I ph / I dark ratio of ~2.5 × 103, responsivity of above 0.3 A/W and detectivity of 1.3 × 1012 Jones, all of which are comparable with those of MoO 3 HTL based perovskite PDs. Graphical abstract Our MoO 3 hole transport layer (HTL) based perovskite PDs using GZO NRs as a scaffold showed a larger light/dark current (I ph / I dark) ratio, higher responsivity and detectivity than those of the undoped ZnO (UZO) NRs/MAPbI 3 devices at zero bias. In addition, a HTL-free perovskite PD prepared by using graphite electrodes shows self-powered PD performances with an I ph / I dark ratio of ~ 2.5 × 103, responsivity of above 0.3 A/W and detectivity of 1.3 × 1012 Jones, all of which are comparable with those of MoO 3 HTL based perovskite PDs. fx1 Highlights • The perovskite photodetector with GZO NRs scaffold showed a larger I ph / I dark ratio, higher responsivity and detectivity than those of the undoped ZnO devices at zero bias. • The enhancements are attributed to the incorporation of Ga elements in ZnO NRs, which reduces defect states of ZnO nanorods. • A HTL-free perovskite PD shows highly self-powered performances with the I ph / I dark ratio of ~2.5 × 103, responsivity of above 0.3 A/W and detectivity of 1.3 × 1012 Jones. [ABSTRACT FROM AUTHOR]

Abstract: SnO2 has been well investigated in many successful state‐of‐the‐art perovskite solar cells (PSCs) due to its favorable attributes such as high mobility, wide bandgap, and deep conduction band and valence band. Several independent studies show the performances of PSCs with SnO2 are higher than that with TiO2, especially in device stability. In 2015, the first planar PSCs were reported with a power conversion efficiency over 17% using a low temperature sol‐derived SnO2 nanocrystal electron transport layer (ETL). Since then, many other groups have also reported high performance PSCs based on SnO2 ETLs. SnO2 planar PSCs show currently the highest performance in planar configuration devices (21.6%) and are close to the record holder of TiO2 mesoporous PSCs, suggesting their high potential as ETLs in PSCs. The main concerns with the application of SnO2 as ETL are that it suffers from degradation in high temperature processes and that its much lower conduction band compared to perovskite may result in a voltage loss of PSCs. Here, notable achievements to date are outlined, the unique attributes of SnO2 as ETLs in PSCs are described, and the challenges facing the successful development of PSCs and approaches to the problems are discussed. [ABSTRACT FROM AUTHOR]

We demonstrate two octamethyl-substituted phthalocyanines, HMe 2 Pc and ZnMe 2 Pc, as dopant-free hole-transport layers for planar pervoskite solar cells. HMe 2 Pc illustrated a very similar HOMO energy level and a slightly smaller band gap compared with that of ZnMe 2 Pc, resulting in perovskite photovoltaic devices with very close open circuit voltage ( V OC ) values based on different phthalocyanine hole transporting materials. Varying the central metals also leads to the HMe 2 Pc film exhibiting higher carrier mobility, better film coverage, and stronger surface hydrophobicity than the ZnMe 2 Pc film, which is consistent with higher short circuit current density ( J SC ) and fill factor ( FF ) values, and better long-term film stability for HMe 2 Pc-based devices. When employed as hole-transport layers by vacuum deposition, the HMe 2 Pc-based devices showed the highest photo conversion efficiency (PCE) of up to 15.59%, which is slightly higher than the 14.88% PCE for ZnMe 2 Pc-based devices. These properties make the easily-synthesized and highly stable octamethyl-substituted phthalocyanines promising candidates as hole-transport materials in perovskite solar cells. [ABSTRACT FROM AUTHOR]

Abstract: Planar perovskite solar cells (PSCs) based on low‐temperature‐processed (LTP) SnO2 have demonstrated excellent photovoltaic properties duo to the high electron mobility, wide bandgap, and suitable band energy alignment of LTP SnO2. However, planar PSCs or mesoporous (mp) PSCs based on high‐temperature‐processed (HTP) SnO2 show much degraded performance. Here, a new strategy with fully HTP Mg‐doped quantum dot SnO2 as blocking layer (bl) and a quite thin SnO2 nanoparticle as mp layer are developed. The performances of both planar and mp PSCs has been greatly improved. The use of Mg‐SnO2 in planar PSCs yields a high‐stabilized power conversion efficiency (PCE) of close to 17%. The champion of mp cells exhibits hysteresis free and stable performance with a high‐stabilized PCE of 19.12%. The inclusion of thin mp SnO2 in PSCs not only plays a role of an energy bridge, facilitating electrons transfer from perovskite to SnO2 bl, but also enhances the contact area of SnO2 with perovskite absorber. Impedance analysis suggests that the thin mp layer is an “active scaffold” selectively collecting electrons from perovskite and can eliminate hysteresis and effectively suppress recombination. This is an inspiring advance toward high‐performance PSCs with HTP mp SnO2. [ABSTRACT FROM AUTHOR]

Tin oxide (SnO 2 ) film with high mobility and good transmittance has been reported as a promising semiconductor material for high performance perovskite solar cells (PSCs). In this study, ultrathin SnO 2 film synthesized by radio frequency magnetron sputtering (RFMS) method at room temperature was employed as hole blocking layer for planar PSCs. The room-temperature sputtered SnO 2 film not only shows favourable energy band structure but also improves the surface topography of fluorine doped SnO 2 (FTO) substrate and perovskite (CH 3 NH 3 PbI 3 ) layer. Thus, this SnO 2 hole blocking layer can efficiently promote electron transport and suppress carrier recombination. Furthermore, the best efficiency of 13.68% was obtained for planar PSC with SnO 2 hole blocking layer prepared at room temperature. This research highlights the room-temperature preparation process of hole blocking layer in PSC and has a certain reference significance for the usage of flexible and low-cost substrates. [ABSTRACT FROM AUTHOR]

Abstract: Planar perovskite solar cells (PSCs) based on low‐temperature‐processed (LTP) SnO2 have demonstrated excellent photovoltaic properties duo to the high electron mobility, wide bandgap, and suitable band energy alignment of LTP SnO2. However, planar PSCs or mesoporous (mp) PSCs based on high‐temperature‐processed (HTP) SnO2 show much degraded performance. Here, a new strategy with fully HTP Mg‐doped quantum dot SnO2 as blocking layer (bl) and a quite thin SnO2 nanoparticle as mp layer are developed. The performances of both planar and mp PSCs has been greatly improved. The use of Mg‐SnO2 in planar PSCs yields a high‐stabilized power conversion efficiency (PCE) of close to 17%. The champion of mp cells exhibits hysteresis free and stable performance with a high‐stabilized PCE of 19.12%. The inclusion of thin mp SnO2 in PSCs not only plays a role of an energy bridge, facilitating electrons transfer from perovskite to SnO2 bl, but also enhances the contact area of SnO2 with perovskite absorber. Impedance analysis suggests that the thin mp layer is an “active scaffold” selectively collecting electrons from perovskite and can eliminate hysteresis and effectively suppress recombination. This is an inspiring advance toward high‐performance PSCs with HTP mp SnO2. [ABSTRACT FROM AUTHOR]

A CoP@Ni(OH) 2 composite with porous nanosheet networks was directly synthesized on carbon cloth, which avoids the usage of any binders and additives. Benefiting from the CoP nanosheet core that could provide fast electron transport pathway and distinctive nano-architecture, this composite achieved a specific capacitance of 1989 F g −1 at a current density of 2.0 A g −1 , good rate capability and cyclic stability. Furthermore, an aqueous asymmetrical CoP@Ni(OH) 2 // AC supercapacitor (ASC) was also successfully assembled. The ASC device exhibited good electrochemical properties including a 1.8 V potential window, a high specific capacitance of 220 F g −1 at a current density of 1 A g −1 and long-term cycling performance. In the meantime, the ASC device also achieved a high energy density of 89.6 Wh kg −1 at a power density of 0.91 kW kg −1 . These results suggest that nano-architectured CoP@Ni(OH) 2 composite has great potential for application in energy storage device. [ABSTRACT FROM AUTHOR]

Reducing the energy loss and retarding the carrier recombination at the interface are crucial to improve the performance of the perovskite solar cell (PSCs). However, little is known about the recombination mechanism at the interface of anode and SnO2 electron transfer layer (ETL). In this work, an ultrathin wide bandgap dielectric MgO nanolayer is incorporated between SnO2:F (FTO) electrode and SnO2 ETL of planar PSCs, realizing enhanced electron transporting and hole blocking properties. With the use of this electrode modifier, a power conversion efficiency of 18.23% is demonstrated, an 11% increment compared with that without MgO modifier. These improvements are attributed to the better properties of MgO‐modified FTO/SnO2 as compared to FTO/SnO2, such as smoother surface, less FTO surface defects due to MgO passivation, and suppressed electron–hole recombinations. Also, MgO nanolayer with lower valance band minimum level played a better role in hole blocking. When FTO is replaced with Sn‐doped In2O3 (ITO), a higher power conversion efficiency of 18.82% is demonstrated. As a result, the device with the MgO hole‐blocking layer exhibits a remarkable improvement of all J–V parameters. This work presents a new direction to improve the performance of the PSCs based on SnO2 ETL by transparent conductive electrode surface modification. [ABSTRACT FROM AUTHOR]

AlGaN/GaN HEMTs with two kinds of p-type metal-oxide (CuO and NiOx) gates have been fabricated, in which the threshold voltage can be modulated effectively. Especially, the threshold voltage of the device shows a 0.7 V positive shift with a high-quality CuO gate layer. Meanwhile, a high on/off current ratio of $\sim 10^{{\mathsf {9}}}$ , a large saturated drain current of ~1030 mA/mm, and an improved transconductance of 200 mS/mm are also achieved. The pulsed transfer characteristics and output characteristics exhibit small hysteresis and ignorable current collapse, signifying an excellent CuO/AlGaN interface. Therefore, CuO can be used as a potential p-type gate for high-performance GaN-based MIS-HEMTs. [ABSTRACT FROM PUBLISHER]

[Display omitted] • Electrostatic self-assembly SnO 2 QDs-TQDs composite materials were fabricated. • SnO 2 QDs-TQDs could effectively engineer the ETL and perovskite/ETL interface. • TQDs modified perovskite exhibits reduced defect density and passivated grain boundaries. • PCE of 23.47 % for PSCs, responsivity (35.54 mA W−1) and response speed (154 ms) for PPDs were achieved. The performance of perovskite solar cells and photodetectors strongly depends on the carrier extraction in the electron transport layer/perovskite interface and the film quality of the perovskite layer. Ti 3 C 2 T x MXene quantum dots, which exhibit both good conductivity of MXene materials and size-dependent tunable optoelectronic properties of quantum dots, were synthesized to form electrostatic self-assembly nanoparticles and further introduced into perovskite optoelectronic devices. The carrier extraction in electron transport layer/perovskite interface was significantly improved, and the defect density of the modified perovskite layer was effectively reduced. These improvements ultimately lead to a remarkable power conversion efficiency of perovskite solar cells increasing from 16.57 % to 23.47 %, and the photodetectors achieve responsivity approaching 35.54 mA W−1 and response speed of 154 ms (rise time) and 120 ms (decay time). Meanwhile, the long-time humidity, thermal and light stress stability of the devices were largely boosted, which originated from the better crystallization and suppressed degradation of the perovskite films. [ABSTRACT FROM AUTHOR]

Light-emitting diodes based on p -SnO 2 / i -MgZnO/ n -ZnO heterojunction have been fabricated. The material properties and the performance of heterojunction device are characterized. Current-voltage characteristics of the device show a diode-like rectifying behavior. Under forward bias, two prominent emission peaks located at 589 nm and 722 nm in the visible region and a weak ultraviolet emission are observed from p -SnO 2 / i -MgZnO/ n -ZnO heterojunction device. As the device is under reverse bias, a broad visible emission band dominates the electroluminescence spectrum at a high current. Furthermore, the emission mechanism has been discussed in terms of energy band structures of the device under forward and reverse biases. [ABSTRACT FROM AUTHOR]

Perovskite solar cells have developed rapidly in recent years as the third generation solar cells. In spite of the great improvement achieved, there still exist some issues such as undesired hysteresis and indispensable high temperature process. In this work, bulk heterojunction perovskite-phenyl-C 61 -butyric acid methyl ester solar cells have been prepared to diminish hysteresis using a facile two step spin-coating method. Furthermore, high quality tin oxide films are fabricated using pulse laser deposition technique at room temperature without any annealing procedure. The as fabricated tin oxide film is successfully applied in bulk heterojunction perovskite solar cells as a hole blocking layer. Bulk heterojunction devices based on room temperature tin oxide exhibit almost hysteresis-free characteristics with power conversion efficiency of 17.29% and 14.0% on rigid and flexible substrates, respectively. [ABSTRACT FROM AUTHOR]

Light-emitting diodes (LEDs) based on ZnO were fabricated on a p -Si substrate by using a pulsed laser deposition system. Significant electroluminescence (EL) improvement was demonstrated with the insertion of an HfO 2 electron blocking layer (EBL) in n -ZnO/ p -Si heterojunctions. Distinct near-band-edge emission at around 392 nm accompanying by a broadly strong visible emission was achieved when a proper thickness of HfO 2 EBL was used. Current-voltage and capacitance-voltage measurements confirmed that a proper thickness of the HfO 2 EBL can effectively balance the injection of electrons and holes, resulting in an increase of radiative recombination in the ZnO active layer and thus enhancing the EL performance of the devices. Five independent emissions corresponding to five different transition processes were proposed to clarify the EL origination of the n -ZnO/HfO 2 / p -Si heterojunction LEDs by Gaussian deconvolutions. It is hoped that results in this work should be helpful for the development of ZnO-based LEDs that can integrate ZnO with the Si planar technology. [ABSTRACT FROM AUTHOR]

Three-dimensional hybrid structure with Ni 3 S 2 nanorod arrays as core material and NiCo hydroxide nanosheets as shell material is fabricated directly on flexible Ni foam. This hierarchical hybrid structure without any additives and binders behaves good electrochemical properties including a high specific capacitance of 1833.7 F g −1 (5.13 F cm −2 ) at a current density of 1 A g −1 , good rate capability with 88.27% capacitance retention at a current density of 20 A g −1 and great cyclic stability. Moreover, an asymmetric supercapacitor (ASC) based on NiCo hydroxide@Ni 3 S 2 hybrid structure on Ni foam as positive electrode and activated carbon as negative electrode is successfully assembled to further evaluate the electrochemical properties of the hybrid structure in a full-cell configuration. The ASC device also performs excellent electrochemical properties including a large potential window of 0–1.8 V, a high specific capacitance of 215.8 F g −1 at a current density of 1 A g −1 and long-term cycling performance. In the meantime, the ASC device also delivers a high energy density of 92.8 Wh kg −1 at a power density of 1.0 KW kg −1 . These results suggest that 3D NiCo hydroxide@Ni 3 S 2 hybrid structure has promising potential for use in high-performance supercapacitor. [ABSTRACT FROM AUTHOR]

TiO 2 nanoflowers composed of nano-needles had been synthesized by hydrothermal method and their field electron emission properties were studied for the first time, which exhibit a low turn-on field of 4.76 V/μm, a high field enhancement factor of up to 5216. This performance was better than that of the as reported TiO 2 nanostructure arrays. The efficient field emission behaviours were found to be not only attributed to their 3 dimensional structures of the nanoflowers but also related to their nano-needle morphology. Besides, self-powered ultraviolet photodetector based on TiO 2 nanoflowers had been fabricated and it showed an obvious response trend in both UV and visible regions with good repeatability and stability, also the photoresponse mechanism at zero bias had been depicted through the energy band theory. [ABSTRACT FROM AUTHOR]

Fiber supercapacitors have attracted public attentions because of their merits of relatively high capacitance density, flexibility and easy integration with various electronic devices. In this work, a flexible coaxial-type fiber solid-state asymmetrical supercapacitor (ASC) based on Ni 3 S 2 nanorod array electrode and pen ink electrode was successfully fabricated. The Ni 3 S 2 nanorod array electrode was synthesized by directly growing Ni 3 S 2 nanorod arrays on a nickel wire through a facile hydrothermal method and the pen ink electrode as negative electrode was synthesized by a simple dip-coating method. The solid-state ASC device presents a stable voltage window of 1.4 V and behaves a high specific capacitance of 34.9 F g −1 (87.25 F cm −1 ) at a scan rate of 10 mV s −1 . Compared with the symmetric supercapacitor (SSC) based on Ni 3 S 2 electrodes, the ASC device provide an increased energy density of 8.2 Wh kg −1 (0.81 mWh cm −3 ) at the power density of 214.6 W kg −1 (21.12 mW cm −3 ). In addition, the ASC device also exhibits excellent electrochemical stability with 93.1% of initial specific capacitance after 3000 consecutive cycles and good mechanical stability. These encouraging results present its great potential in flexible solid-state energy storage devices. [ABSTRACT FROM AUTHOR]

CsPbBr3 Single Crystal High pressure exerted on CsPbBr3 single crystal using diamond anvil cell leads to improved photoluminescence intensity due to the decreased dynamic Rashba splitting. Application of higher pressure transforms it into a pure indirect bandgap phase, which can be maintained at near‐ambient pressure. These phenomena provide a novel framework to understand the optoelectronic properties of perovskite materials. More details can be found in article number 2201554 by Junbo Gong, Zengming Zhang, Xudong Xiao, and co‐workers. [ABSTRACT FROM AUTHOR]

Anatase TiO 2 film with 3D network nanoporous structure consisted of 1D nanowires is obtained on SnO 2 :F (FTO) glass substrate by in-situ hydrothermal synthesis and applied in mesoporous perovskite (CH 3 NH 3 PbI 3 ) solar cell. A thin Ti film is deposited on FTO substrate by magnetron sputtering before the hydrothermal treatment with sodium hydroxide solution. Then, a layer of network nanoporous TiO 2 (NT) film is formed. The efficiency of perovskite solar cell based on this 3D structure with one-step sintering can be optimized to 9.19%. The NT film consisted of 1D TiO 2 nanowires is beneficial to the transmission of charge carriers and the infiltration of hole transport material. And this one-step sintering process can reduce the interface defects and enhance the fill factor of the device. Then, we further optimize the surface of NT layer through TiCl 4 post-treatment. The post-treatment can optimize the carrier separation and the deposition of perovskite layer, thus improving the open-circuit voltage (V oc ) and short-circuit current density (J sc ) of perovskite solar cell. As a result, the value of J sc gets an enhancement of 45.63% and the efficiency of perovskite solar cell reaches up to 12.78%. [ABSTRACT FROM AUTHOR]

In this paper, a thin layer of high work function CuS was introduced to the interface between the anode and hole transporting layer (HTL) to modify the indium tin oxide (ITO) anode. Modified ITO substrates possess a higher work function, a lower sheet resistance and a negligible loss in transparency. More importantly, a thin layer of CuS can also benefit for the hole transporting of the device. Polymer solar cells (PSCs) utilizing modified ITO anodes exhibit a significant enhancement in power conversion efficiency ( PCE ) and air stability compared to devices with normal ITO anodes. This anode modification strategy applies to different active layer systems. Anode-modified devices with poly (3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PC 61 BM) as the active layer exhibit a PCE of 3.5%, while poly(4,8-bis(5-(2-ethyl-hexyl)-thiophene-2-yl)-benzo[l,2-b:4,5-b′] dithiophene-alt-alkylcarbonyl-thieno[3,4-b]thiophene) (PBDTTT-C-T) and [6,6]-phenyl-C71-butyric acid methyl ester (PC 71 BM) system shows a PCE of 7.4%. As a result, this work provides a good compatibility for modification of ITO by a thin layer of CuS in PSCs to achieve better performance. [ABSTRACT FROM AUTHOR]

In this work, three dimensional Co 9 S 8 nanorod@Ni(OH) 2 nanosheet core-shell structure is directly fabricated on flexible carbon cloth by a simple low temperature hydrothermal method. This structure with good electrochemical performance could be applied for supercapacitor electrode material. Firstly, this three dimensional structure possesses high specific capacitance of 1620 F g −1 , which is 1.7 times of the specific capacitance of the pure Ni(OH) 2 electrode and 2.5 times of that of the pure Co 9 S 8 electrode. Secondly, this hybrid electrode exhibits a very high energy density of 70.0 Wh Kg −1 at the power density of 305.7 W kg −1 . In addition, the hybrid electrode displays good cycling stability with 104.5% of the initial capacitance after 2000 continuous cycles. Furthermore, the hybrid electrode with three dimensional structure possesses excellent flexibility and has almost the same cyclic voltammetry curve under different bending angles. Thus, the designed electrode holds great promises for light weight, flexible, high energy density supercapacitor applications. [ABSTRACT FROM AUTHOR]

An organic-inorganic photodetector based on poly(3,4-ethylenedioxythiophene) (PEDOT:PSS)/SnO microwires p- n heterojunction has been fabricated. The photodetector reveals excellent rectifying behavior, and it exhibits a significant photoresponse to blue light of 450 nm without bias, which indicates its high potential application values. The PEDOT:PSS/SnO heterojunction photodetector shows excellent stability and reproducible characteristics from the time-dependent photoresponse spectrum. The mechanism of the blue-sensitive photodetector is discussed in terms of band diagram of the heterojunction and the material properties. [ABSTRACT FROM AUTHOR]