Halogenation of the Side Chains in Donor‐Acceptor Based Small Molecules for Photovoltaic Applications: Energetics and Charge‐Transfer Properties from DFT/TDDFT Studies

Abstract

Incorporation of halogen atoms in conjugated polymer and small molecule (SM) based donors has been a practical approach to improve the efficiency of devices. In this report, we present a comprehensive study on the effects of halogenation of the side chains of three SM donors on the structural, optoelectronic, and charge-transfer properties of donors and donor/PC 61 BM blends. Starting with experimentally prepared three novel SM donors with three different lateral side chains, we have computationally designed three halogenated donor SMs for each of those three SMs. Properties such as HOMO/ LUMO energies, open-circuit voltages, and charge transfer/ recombination rates are calculated. Halogenated systems have deeper HOMO values than parent systems, and as a result, larger open-circuit voltages are obtained for these new systems. In the halogenated systems, rates of charge-transfer and charge-recombination are larger and smaller, respectively, than in the parent systems. All these indicate better photovoltaic performances of these halogenated SM-based devices.

Modeling of the photophysical and photovoltaic properties of an active layer based on the organic composite poly(2‐methoxy‐5‐(2‐ethyl‐hexyloxy)‐1,4‐phenylene‐vinylene) (MEH‐PPV)–poly(3‐hexylthiophene) (P3HT): (6,6)‐phenyl C61 butyric acid methyl ester (PCBM)

“…Thus, CAM-B3LYP may be the most suitable function that can be used in excited state calculations. Where we notice that the CAM-B3LYP has been used in numerous theoretical studies of organic conjugated (D-A) systems, which enhances the supply of their utility [2,14,[27][28][29][30][31]. For this reason, we choose to use CAM-B3LYP for excited-state calculations.…”

Effect of Cyano and Tetrazole Side Groups on the Photophysical and Chelating Properties of Anthracene‐Based Polymers

“…This is because of the multiple advantages the conjugated macromolecules offer, such as their good physicochemical and electrical properties as well as the relatively low manufacturing costs which provide a solution for mass production compared to small-molecule organic semiconductors. [1] Therefore, conjugated polymers have found their application in different fields, e. g., light-emitting devices, [2][3][4] photovoltaic materials [5,6] and thin film transistors… [7,8] Recently, the attention has been drawn to the use of conjugated polymers as chemical sensors. [9] Researchers take advantages of the diversity of the sensors' responses which can be naked-eye remarkable color changes, a turn-on/off of the fluorescence [10] or variations in the absorption spectrum… [11] Over the different chemosensors, polymer fluorescent sensors have shown great advantages in terms of sensitivity, speed of analysis, low cost, and real-time detection.…”

“…Therefore, conjugated polymers have found their application in different fields, e. g., light‐emitting devices, [2–4] photovoltaic materials [5,6] and thin film transistors… [7,8] …”

Anthracene and β‐Cyclodextrin Based Supramolecular Semi‐Conducting Thin Film: Effect of the Encapsulation on the Optical and Electrical Properties

“…Due to their unique properties such as the solubility, the flexibility, the light weight and the relative ease of synthesis, organic semiconductors have found a large field of applications such as organic field effect transistors (OFETs), [1,2] organic lightemitting diodes (OLEDs), [3,4] organic photovoltaic cells (OPVs) [5,6] and sensors. [7,8] These materials can be also easily used in solution processing techniques that are relatively simple like inkjet printing and spin coating.…”