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The quality of the photoactive layer gravely affects the characteristics and stabilities of photovoltaic device. Here, by introducing polyethylene glycol (PEG) into the methylammonium lead trihalide (MAPbI 3) precursor solution, we fabricate high-quality MAPbI 3 perovskite film with high coverage and large grain size. By adjusting the PEG concentration into the perovskite film, the hole-conductor-free mesoporous perovskite solar cell with carbon electrode exhibits a boosted power conversion efficiency of 11.62%, which originates primarily from the enhancements of light absorption and acceleration of carriers transfer. Meanwhile, hygroscopic PEG protects the perovskite film from moisture, which leads to the perovskite film and corresponding device exhibit superior stability. This work confirms a high-efficiency and feasible strategy using polymer materials to enhance the performance in power conversion efficiency and stability of perovskite solar cells. Image 1 • Large grain size and high coverage perovskite film is induced by PEG additives. • Optical and electrical properties of PSC with high quality perovskite film are enhanced. • Both PEG-MAPbI 3 film and corresponding device exhibit superior stability in air with a humidity of approximately 50%. • Hygroscopic PEG and hydrophobic carbon electrode synergistically prevent perovskite layers from moisture. [ABSTRACT FROM AUTHOR]

Hole-conductor-free perovskite solar cells (PSCs) based on carbon counter electrode were fabricated under a high humidity air environment and the performance of Cs+ doping in methylammonium lead iodide perovskite (Cs x MA 1- x PbI 3) as light absorber layer was investigated and discussed. After the doping of Cs+, the excellent morphology, crystallinity and light absorption of perovskite thin films were observed by corresponding test methods, leading to the higher short-circuit current density and open-circuit voltage in the relevant devices. However, excessive Cs+ doping can damage the performance of PSCs. The optimized device with x = 0.05, exhibited open-circuit voltage of 956 mV, short-circuit current density of 21.73 mA/cm2, fill factor of 0.509 and the power conversion efficiency (PCE) of 10.57% under AM 1.5G illumination showing a 16% enhancement than pure MAPbI 3 devices. The PSCs based on carbon counter electrode also showed high stability, despite being stored under ambient air without encapsulation. After 1000 h, the Cs 0.05 MA 0.95 PbI 3 devices maintained more than 90% of their initial PCE. The long-term stability can be attributed to the synergistic interaction of Cs+ on the solid solution strengthening of MAPbI 3 and the protection of the hydrophobic carbon electrode on the perovskite active layer. [ABSTRACT FROM AUTHOR]

MgTiO 3 -coated TiO 2 mesoporous scaffold layers were fabricated and applied in perovskite solar cells (PSCs) based on carbon counter electrode (CCE), in which TiO 2 mesoporous layers were treated with different concentration of Mg2+ solution. Compared with PSCs based on pure TiO 2 mesoporous layer, the open circuit voltage (V oc) and circuit photocurrent density (J sc) of MgTiO 3 /TiO 2 -based devices significant improved. Intensive characterizations including scanning electron microscopy, electrochemical impedance spectroscopy can confirm that the presence of MgTiO 3 shell layer can't only retard charge recombination at CH 3 NH 3 PbI 3 /TiO 2 interface, but also have a strong effect on the perovskite film growth. Based on the optimized treating concentration of 0.10 M, power conversion efficiency (PCE) of 10.39% could be achieved for the hole-conductor-free PSCs with excellent long-term stability, suggesting immense potential for large-scale industrial production in the future. Image 10988843 • MgTiO 3 -coating TiO 2 mesoporous layers were fabricated and applied in PSCs. • Carbon replaces the noble metal as counter electrode for saving cost. • MgTiO 3 shell can retard charge recombination in PSCs. • The optimized devices show high V oc of 0.95 V and PCE of 10.39%. • The PSCs exhibited excellent long-term stability under high humidity of ∼50%. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Organic-inorganic hybrid perovskite solar cells (PSCs) have become a research hotspot due to the impressive photovoltaic performance. The perovskite film plays an extremely important role in the light-to-electricity conversion, meanwhile, the stability of PSCs is also an important factor affecting the application of devices. Here we demonstrate a kind of stable PSCs by using simple solution-process in an air enviroment with about 45% relative humidity. Firstly, the NH 4 Cl was added to the perovskite precursor solution to adjust the kinetics of crystallization and growth of active layer, and then obtain high-quality CH 3 NH 3 PbI 3 perovskite films. Hydrophobic carbon electrode was used to protect the perovskite active layers and further improve the stability of PSCs, which optimized the structure of the devices at the same time. We adjusted the amount of NH 4 Cl in the perovskite precursor solution (PbI 2 : CH 3 NH 3 I: NH 4 Cl = 1: 1: x (x = 0 ∼ 1), and investigated the effect of that on the properties of perovskite active layers and PSCs. The above results showed that the devices achieved fully covered perovskite thin films and improved the photovoltaic performance of PSCs when the NH 4 Cl additive was x = 0.8. The short-circuit current density (J sc), fill factor (FF) and power conversion efficiency (PCE) were significantly enhenced. Under the condition of ambient air and no encapsulation, the PSCs exhibited good stability after 576 h test, and the PCE was still about 96% of the initial efficiency. [ABSTRACT FROM AUTHOR]

Abstract The hole-transporting materials and noble metal employed in normal perovskite solar cells (PSCs) limited their practical application. In this work, the high photovoltaic performance hole-conductor-free PSCs based on carbon counter electrode were fabricated in air atmosphere with high humidity condition (HR) around 55%. An efficient TiO 2 blocking layers (BL-TiO 2) was prepared by spin-coating the precursor solutions containing ethanol (CH 3 CH 2 OH), titanium n-butoxide (Ti(OC 4 H 9) 4) and diethanolamine (C 4 H 11 NO 2 DEA) with different molar ratios (CH 3 CH 2 OH: Ti(OC 4 H 9) 4 : DEA = 30: 1: x) on TiCl 4 per-treated FTO glass. When adding DEA in Ti precursor solution, it would revamp the cracks of blocking layer, the suitable alkaline environment provided by DEA can contribute to growing compact BL-TiO 2. Electrical impedance measurements were performed to investigate the kinetic issues of charging transport performance in PSCs with different amount of DEA. The optimized PSCs exhibited a short-circuit photocurrent density of 22.71 mA/cm2, open-circuit voltage of 954 mV, fill factor of 0.55 and power conversion efficiency (PCE) of 11.92% when DEA molar ratios x = 0.75. The PCE of optimized PSCs retained about 90% after 21 days in air with HR around 55%. The low cost and outstanding properties endow the present carbon counter electrode based PSCs with immense application potentials. Graphical abstract Image 1 Highlights • The PSCs based on carbon counter electrode were fabricated in air atmosphere. • Hole transport layer and noble metal electrode were no employed in PSCs. • The power conversion efficiency of PSCs was achieved 11.92% with optimum TiO 2 blocking layer. • The optimized PSCs had a long-term stability stored in fabricate condition. [ABSTRACT FROM AUTHOR]

In this work, hole-conductor-free mixed organic cation perovskite solar cells based on carbon counter electrode were fabricated under air atmosphere with high humidity condition around 50%. The photovoltaic performance of the perovskite solar cells with mixed organic cation perovskite (FA) x (MA) 1− x PbI 3 by chemical modification the molar ratios x were demonstrated. The light harvesting abilities and crystal morphology could be controlled with x from 0 to 0.4 which resulted in a corresponding diversification of photoelectric properties in perovskite solar cells. Electrical impedance measurements were performed for investigating the electron transport issues in perovskite solar cells with various x . The optimized perovskite solar cells delivered a short-circuit photocurrent density of 21.63 mA/cm 3 , open-circuit voltage of 980 mV, fill factor of 0.45 and overall conversion efficiency of 9.53% as x  = 0.3. The long-term stability of the optimized perovskite solar cells was exhibited and the overall conversion efficiency retained about 91% after 49 days in air with humidity around 50%. The hole-conductor-free perovskite solar cells based on carbon counter electrode have low-cost and bring a prosperous application foreground in the future photovoltaic community. [ABSTRACT FROM AUTHOR]

Aimed at the facile detection of lengthy DNA molecules, an easily operated sandwich-type electrochemiluminescence (ECL) DNA biosensor was constructed on a glassy carbon electrode (GCE) based on CdTe quantum dots coated hollow ZnO nanoparticles (CdTe–ZnO NPs)–S2O82− ECL system in this work. To fabricate a high-performance protocol, the GCE surface was successively modified by graphene nanosheet (GS), carbon nanotube (CNT) and gold nanoparticles (AuNPs) to form AuNPs dotted CNT–GS composites (Au@CNT–GS) platform, which improved the electronic transmission rate as well as increased the amount of immobilized capture probe CMV-F (S1). For further ultrasensitive, stable and low-potential ECL detection, CdTe–ZnO NPs were synthesized, and employed to label signal probe T7 promoter (S3). Based on the hybridization effect, the immobilized capture probe S1, target DNA and labeled signal probe S3 formed a sandwich-type DNA complex, which produced the ECL emission in the presence with S2O82− coreactant. Under optimal conditions, the DNA ECL biosensor showed a good linear range over 10−14 M to 10−19 M with a low detection limit of 0.61 × 10−19 M. The proposed strategy demonstrates a reproducible, stable, and potent method that can be expanded to detect the genome which exists in living cells. [ABSTRACT FROM AUTHOR]

Thin films of molecularly imprinted sol–gel polymer with specific binding sites for trichlorfon were prepared, fixed on glassy carbon electrodes and used as recognition material. The binding characteristic of the imprinted films to trichlorfon was evaluated by equilibrium binding experiments; and, the morphology was studied by scanning electronic microscope. A novel electrochemical sensor for determination of trichlorfon was developed based on the reaction between trichlorfon and the molecularly imprinted sol–gel film, which was a modified glassy carbon electrode. The sensor displayed excellent selectivity and high sensitivity. The linear response range of the sensor was 10 −8 –10 −6 g mL −1, and the limit of detection was 2.8 × 10 −9 g mL −1. The relative standard deviation for the determination of 10 −7 g mL −1 trichlorfon was 3.5%. The sensor was applied to the determination of trichlorfon in vegetables with satisfactory results. [ABSTRACT FROM AUTHOR]