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Simple and low-cost two-dimensional (2D) materials are of great interest considering their wide use in various device applications. Here, we present the application of 2D materials, i.e., graphene oxide (GO), molybdenum disulfide (MoS 2), and tungsten disulfide (WS 2) as hole transport layer (HTL) in non-fullerene acceptors (NFAs) organic photovoltaics (OPVs) using device simulation. The numerical simulation was carried out using SCAPS-1D and specifically focused on the effect of thickness and defect density at the active layer on the photovoltaic characteristics of the devices. In addition, the influence of defect density at the HTL/active layer interface on the device performance was also studied. After conducting a series of optimization, an optimum power conversion efficiency (PCE) of 15.89%, 20.05%, and 23.55% was achieved for NFA-based OPV with GO, MoS 2 , and WS 2 , respectively. This work provides a practical explanation of the feasible performance enhancement and critical design parameters for OPV devices. The results showcase the potential application of 2D materials as low-cost HTL for high-efficiency organic solar cells. [Display omitted] • Device modelling 2D – HTM of non-fullerene acceptor organic photovoltaic was comprehensively performed. • The influence of physical parameters on NFA – OPVs performance was thoroughly discussed. • After optimization, we obtained PCE of 15.89%, 20.05%, and 23.55% for GO, MoS 2 , and WS 2 as HTM, respectively. • The study promotes future OPVs optimization and performance enhancement. [ABSTRACT FROM AUTHOR]

Molecular doping of organic semiconductors is often used to enhance their charge transport characteristics. Despite its success, however, most studies to date concern p‐doping with considerably fewer reports involving n‐dopants. Here, n‐doping of organic thin‐film transistors (OTFTs) based on several non‐fullerene acceptor (NFA) molecules using the recently developed diquat (DQ) as a soluble molecular dopant is reported. The low ionization potential of DQ facilitates efficient electron transfer and subsequent n‐doping of the NFAs, resulting in a consistent increase in the electron field‐effect mobility. Solution‐processed BTP‐eC9 and N3‐based OTFTs exhibit significant increase in the electron mobility upon DQ doping, with values increasing from 0.02 to 0.17 cm2 V–1 s–1 and from 0.2 to 0.57 cm2 V–1 s–1, respectively. A remarkable electron mobility of >1 cm2 V–1 s–1 is achieved for O‐IDTBR transistors upon optimal doping with DQ. The enhanced performance originates primarily from synergistic effects on electronic transport and changes in morphology, including: i) significant reduction of contact resistances, ii) formation of larger crystalline domains, iii) change of preferred crystal orientation, and iv) alteration in molecular packing motif. This work demonstrates the universality of DQ as an electronic additive for improving electron transport in OTFTs. [ABSTRACT FROM AUTHOR]

Hydrogen is attractive as an abundant source for clean and renewable energy. However, due to its highly flammable nature in a range of concentrations, the need for reliable and sensitive sensor/monitoring technologies has become acute. Here a solid‐state hydrogen sensor based on solution‐processable p‐type semiconductor copper thiocyanate (CuSCN) is developed and studied. Sensors incorporating interdigitated electrodes made of noble metals (gold, platinum, palladium) show excellent response to hydrogen concentration down to 200 ppm while simultaneously being able to operate reversibly at room temperature and at low power. Sensors incorporating Pd electrodes show the highest signal response of 179% with a response time of ≈400 s upon exposure to 1000 ppm of hydrogen gas. The experimental findings are corroborated by density functional theory calculations, which highlight the role of atomic hydrogen species created upon interaction with the noble metal electrode as the origin for the increased p‐type conductivity of CuSCN during exposure. The work highlights CuSCN as a promising sensing element for low‐power, all‐solid‐state printed hydrogen sensors. [ABSTRACT FROM AUTHOR]

Efficiencies of organic solar cells have practically doubled since the development of non‐fullerene acceptors (NFAs). However, generic chemical design rules for donor‐NFA combinations are still needed. Such rules are proposed by analyzing inhomogeneous electrostatic fields at the donor–acceptor interface. It is shown that an acceptor–donor–acceptor molecular architecture, and molecular alignment parallel to the interface, results in energy level bending that destabilizes the charge transfer state, thus promoting its dissociation into free charges. By analyzing a series of PCE10:NFA solar cells, with NFAs including Y6, IEICO, and ITIC, as well as their halogenated derivatives, it is suggested that the molecular quadrupole moment of ≈75 Debye Å balances the losses in the open circuit voltage and gains in charge generation efficiency. [ABSTRACT FROM AUTHOR]

Semi-transparent (ST) tandem organic solar cells (OSCs) are typically exhibiting a trade-off between efficiency and average visible transmittance (AVT), which can be minimized by the appropriate selection of transparent contacts and absorbing materials in the sub-cells. Herein, we demonstrate efficient and highly transparent hetero-tandem OSCs constructed by stacking PBDT[2F]T:PC 71 BM and PCE10:PC 61 BM active layers as front-cell and back-cell, respectively. Optical and electrical simulations show that the PBDT[2F]T and PCE10-based sub-cells possess potential as ST and reflective tandem OSCs. With the aid of the simulations, we could fabricate reflective tandem OSCs with an efficiency of up to 8.3%. Furthermore, a ST tandem OSC, employing conductive silver nanowire top contact, achieved an AVT of 49.2%, efficiency of 5.3%, and high light utilization efficiency (LUE) of 2.61% under 1 sun, AM1.5G spectral illumination. This study demonstrates the importance of the sub-cells choices for developing ST tandem solar cells with a good balance of AVT and PCE, paving the way for solar windows of high performance. [Display omitted] • Optical and electrical simulations performed to aid reflective and semi-transparent tandem OSCs fabrication. • Fabrication of tandem based on PBDT[2F]T:PC 71 BM and PCE10:PC 61 BM blends with PCE higher than their single-cells (8.2%). • Semi-transparent tandem device with a very high AVT of nearly 50%, in agreement with optical simulation. • The semi-transparent tandem based on PBDT[2F]T:PC 71 BM and PCE10:PC 61 BM blends achieved high PCE of 5.3% and LUE of 2.61%. [ABSTRACT FROM AUTHOR]

Chemical Design Rules for Non-Fullerene Acceptors in Organic Solar Cells (Adv. Design rules, donor-acceptor interface, non-fullerene acceptors, organic solar cells Keywords: design rules; donor-acceptor interface; non-fullerene acceptors; organic solar cells EN design rules donor-acceptor interface non-fullerene acceptors organic solar cells 1 1 1 11/26/21 20211125 NES 211125 B Non-Fullerene Acceptors b In article number 2102363, Denis Andrienko and co-workers summarize the chemical design rules of non-fullerene acceptor molecules for use in efficient organic solar cells. [Extracted from the article]