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Organic photodetectors (OPDs) have been widely studied to achieve high performance for light detection. Photocurrent, a key parameter determining the responsivity of photodetectors, has rarely been investigated for enhancing the performance. Herein, three small molecules were systematically designed and synthesized for use as OPDs. Through the introduction of S…O non-covalent conformational locks and changing side chains, the physicochemical properties of the materials, especially the light absorption range and blend film morphology, were effectively tuned, leading to enhanced photocurrent and thus a higher responsivity (from 0.07 A W−1 to 0.29 A W−1 at −0.5 V bias), which is among the highest values for OPDs. The mechanism was systematically investigated with different techniques including ultrafast transient absorption, vertical phase segregation, and charge transport mobility, which helps to elucidate the differences of the photodetectors' performances. This contribution presents an efficient strategy to enhance the responsivity and sheds light on understanding the structure–property relationship of organic semiconductors for use as OPDs. [ABSTRACT FROM AUTHOR]

Realizing high sulfur loading while ensuring high sulfur utilization holds the key to enhancing the practical energy density of Li–S batteries. Inspired by the reinforced concrete structure in buildings, a facile route for the synthesis of a lightweight and binder-free electrode, composed of lignin fibers@carbon nanotubes as sulfur hosts and graphene as the current collector, was reported. Benefiting from the efficient polysulfide-anchoring performance of lignin fiber, 3D conductive frameworks of CNTs and the depolarization effect of graphene, the Li–S batteries using this electrode exhibited an unprecedented discharge capacity as high as 1632 mA h g−1 at 0.1C and enhanced capacity of 987 mA h g−1 after 500 cycles at 1.0C. Furthermore, even up to a sulfur loading of 9.2 mg cm−2, this electrode still maintained a highly reversible capacity of 668.8 mA h g−1 at 0.5C after 100 cycles, corresponding to 91.5% capacity retention. This lightweight and flexible electrode appears to be a scalable solution for obtaining high energy density Li–S batteries. [ABSTRACT FROM AUTHOR]

Non-fullerene organic solar cells (OSCs) have attracted great attention due to their advantages including tunable light absorption and low cost fabrication. Many important strategies have been used to achieve high performing OSCs including increasing the charge transport mobility and reducing the energy loss (Eloss). In this contribution, two wide bandgap small molecular acceptors (IDTzCR and IDTCR) were designed and synthesized for OSCs. Through replacing the thiophene moieties with thiazole ones, charge transport mobility was increased due to introducing S…N noncovalent conformational locks, resulting in a significant enhancement of photovoltaic performances. Furthermore, IDTCR based OSCs afforded a record low Eloss value for “narrow bandgap donor:wide bandgap acceptor” systems due to the small LUMO/LUMO energy offset. This contribution showed a novel method to achieve excellent wide bandgap acceptors for OSCs and sheds lights on understanding the relationship between the materials properties and device performances. [ABSTRACT FROM AUTHOR]

In this contribution, we developed a novel type of IDT-based small molecular acceptor, IDT-Tz, using thiazole as π-bridges. Through employing thiazole units as the π-bridges, nitrogen…sulfur noncovalent conformational locks were introduced to enhance the rigidity and planarity of the backbone, and thus reduce the reorganization energy, increase the charge transport mobility, and enhance the photovoltaic performance. The differences between the IDT-Tz and IDT-T based solar cells were fully investigated to understand the influences of the nitrogen…sulfur noncovalent conformational locks. The organic solar cells based on the IDT-Tz electron acceptor exhibit power conversion efficiencies (PCEs) as high as 8.4%, which is significantly higher than the PCE (4.1%) of the IDT-T based devices. This work demonstrated a novel strategy for enhancing the PCE of organic solar cells through introducing noncovalent conformational locks, which will be promising in designing novel high-performance non-fullerene materials. [ABSTRACT FROM AUTHOR]

Open circuit voltage (Voc) is a critical parameter for ternary organic solar cells, while its mechanism is obscure. Here we employed two non-fullerene molecules TPE-4PDI and FT-2PDI (perylenediimide, a PDI-based small molecule) to form acceptor alloys with ITIC-Th (indacenodithieno, an IDDT-based small molecule) for ternary systems. The results demonstrated that the experimental Voc values fit the simulation data accurately based on the equation not only in our new ternary systems but also in other reported small molecular alloy based ternary systems. More importantly, TPE-4PDI is more efficient to enhance the Voc of ternary solar cells as the third component than FT-2PDI, since TPE-4PDI possesses a larger quasi frontier orbital density (Ne) value. Thus, upon tuning the weight ratio of the TPE-4PDI:ITIC-Th acceptor alloy, high performance ternary solar cells with an efficiency over 11% were achieved. This contribution has shed light on understanding the mechanisms of ternary solar cells and demonstrated a method for enhancing Voc efficiently to achieve high performance solar cells. [ABSTRACT FROM AUTHOR]

A collaborative manipulation strategy of proper heat treatment and self-customized hydrofluoroether-based electrolyte design has been proposed for boosting the sodium-ion storage kinetics of Prussian white cathodes. Improved monoclinic phase stability and electrolyte-cathode compatibility are responsible for an impressive discharge capacity of 148.4 mA h g -1 and excellent electrode reversibility.

To produce water-stable Ni-rich lithium nickel cobalt aluminum oxides (LiNi x Co y Al 1- x - y O 2 , x > 0.85, NCAs), the formation of trilithium phosphate (Li 3 PO 4 )-coated layers on the NCA surfaces was attempted through the use of a surface reaction in a mixture of ethanol and water and a post-heat treatment at 350 and 400 °C. Based on the results of X-ray photoelectron spectroscopy (XPS), the coated layers consisted of nickel phosphate (Ni 3 (PO 4 ) 2 ) and Li 3 PO 4 . The coated NCA surface could have sufficient water stability to maintain the cathode performance in a water slurry for 1 day. In addition, the coated layers formed on the NCA surfaces did not block Li + -ion transfer through the Ni 3 (PO 4 ) 2 /Li 3 PO 4 -coating layers and enhanced the high-rate discharge performance., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Recently a water-based polymer binder has been getting much attention because it simplifies the production process of lithium ion batteries (LIBs) and reduce their cost. The surface of LiNi a Co b Al 1- a - b O 2 ( a > 0.85, NCA) cathode with a high voltage and high capacity was coated doubly with water-insoluble titanium oxide (TiO x ) and Li 2 CO 3 layers to protect the NCA surface from the damage caused by contacting with water during its production process. The TiO x layer was at first coated on the NCA particle surface with a tumbling fluidized-bed granulating/coating machine for producing TiO x -coated NCA. However, the TiO x layer could not coat the NCA surface completely. In the next place, the coating of the TiO x -uncoated NCA surface with Li 2 CO 3 layer was conducted by bubbling CO 2 gas in the TiO x -coated NCA aqueous slurry on the grounds that Li 2 CO 3 is formed through the reaction between CO 3 2- ions and residual LiOH on the TiO x -uncoated NCA surface, resulting in the doubly coated NCA particles (TiO x /Li 2 CO 3 -coated NCA particles). The Li 2 CO 3 coating is considered to take place on the TiO x layer as well as the TiO x -uncoated NCA surface. The results demonstrate that the double coating of the NCA surface with TiO x and Li 2 CO 3 allows for a high water-resistance of the NCA surface and consequently the TiO x /Li 2 CO 3 -coated NCA particle cathode prepared with a water-based binder possesses the same charge/discharge performance as that obtained with a "water-uncontacted" NCA particle cathode prepared using the conventional organic solvent-based polyvinylidene difluoride binder., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)