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Increased CO 2 emissions on the earth causing global warming and climate change have provided a thrust to explore Li−CO 2 battery chemistry, where CO 2 is used as an energy carrier. In addition, the occurrence of CO 2 as a major natural abundant gas in the Martian atmosphere opens the possibility of using Li−CO 2 batteries for interplanetary Mars missions. In this work, we aim to investigate facile and inexpensive candle soot carbon nanoparticles as a cathode catalyst against commercially available multiwalled carbon nanotubes (MWCNTs) for stable and high-performance Li−CO 2 batteries for Mars exploration. The unique interconnected morphology and higher surface area of candle soot nanoparticles facilitate better reversibility (more than 80 cycles) compared to MWCNTs even at a high current density of 200 mA g −1 with a cutoff capacity of 500 mAh g −1 . The full discharge capacity for candle soot nanoparticles was measured to be 5318 mAh g −1 with a coulombic efficiency of 42% as compared to 16% for MWCNTs. The rate capability studies were performed to establish the ability to operate the system reversibly at different current densities in a simulated Martian atmosphere. The outcome of this study paves the way toward developing a candle soot cathodebased practicable Li−CO 2 battery for utilization on Mars.

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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.

This report presents the effect of insertion of four different π bridges, furan, thienothiophene, thiophene, and thiazole, into a random benzodithiophene (BDT)-fluorinated-thienothiophene (TT-F) based donor. Starting from a structure of synthesized donor (D)–acceptor (A) random copolymer with 3:1 ratio, we have designed four D−π–A systems with four different π bridges. Structural, optoelectronic, and charge transport/transfer properties of these donors and donor/NDI (NDI = poly­[N,N′-bis­(2-hexyldecyl)-naphthalene-1,4,5,8-bis­(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)) blends are investigated using DFT and TD-DFT methodologies. Our results show that the thiazole based TzP1 oligomer has the deepest HOMO value resulting in the highest open circuit voltage among all systems. The maximum absorption wavelengths of π-linked systems are red-shifted compared to the parent molecule. Rates of charge transfer and charge recombination are the highest and smallest in case of the thiazole/NDI blend system. In addition, hole mobilities in thiophene, thienothiophene, and thiazole based systems are larger than in the parent system. The results indicate that the thiazole unit among the four π bridge units is the most suitable for active layer construction.