An opposite interfacial exciton dissociation behavior at the metal (Al)/organic cathode interface in regular and inverted organic solar cells (OSCs) was analyzed using transient photocurrent measurements. It is found that Al/organic contact in regular OSCs, made with the blend layer of poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl]-[3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]-thiophenediyl]] (PTB7):3′H-Cyclopropa [8,25][5,6] fullerene-C70-D5h(6)-3′-butanoicacid,3′-phenyl-,methyl ester (PC₇₀BM), always hampers the electron collection. However, this is not observed in their reverse geometry OSCs fabricated using the same PTB7:PC₇₀BM blend system. The detrimental interfacial exciton dissociation in regular OSCs originates the compensation of field drifted photo-generated electrons at Al/organic interface. The unfavorable interfacial exciton dissociation can be eliminated, e.g., by interposing a ZnO-based interlayer between Al and organic layer, attaining an efficient electron collection, thereby power conversion efficiency.

The effects of doping on the electronic and magnetic properties of the quaternary Heusler alloy TiZrCoIn were investigated by first-principles calculations. Results showed that the appearance of half-metallicity and negative formation energies are associated in all of the TiZrCoIn_1−xGe_x compounds, indicating that Ge doping at Z-site increases the stability without damaging the half-metallicity of the compounds. Formation energy gradually decreased with doping concentration, and the width of the spin-down gap increased with a change in Fermi level. TiZrCoIn_0.25Ge_0.75 was found to be the most stable half-metal. Its Fermi level was in the middle of the broadened gap, and a peak at the Fermi level was detected in the spin majority channel of the compound. The large gaps of the compounds were primarily dominated by the intense d-d hybridization between Ti, Zr, and Co. The substitution of In by Ge increased the number of sp valence electrons in the system and thereby enhanced RKKY exchange interaction and increased splitting. Moreover, the total spin magnetic moments of the doped compounds followed the Slater–Pauling rule of M_t = Z_t − 18 and increased from 2 μ_B to 3 μ_B linearly with concentration.

Two novel small molecular non-fullerene acceptors, BF-PDI2 and BF-PDI4, respectively, carrying two and four peripheral perylenediimide moieties, are obtained from appositely functionalized 9,9′-bifluorenylidene and perylenediimide via Suzuki cross-coupling reaction. Owing to their twisted molecular structures, these acceptors possess good solution processability and exhibit relatively weak intermolecular interactions in both solution and the solid state as evidenced from their spectral characteristics. Both display an optical bandgap of 1.94 eV, and their LUMOs as estimated from electrochemical data are −3.83 and −3.92 eV for BF-PDI2 and BF-PDI4, respectively. Both can be utilized as a fullerene acceptor replacement in bulk heterojunction organic solar cells with a polymer donor, PBT7-Th, affording reasonable power conversion efficiencies of 2.46 and 4.43%, respectively.

In this study, the interface structures, atom-resolved magnetism, density of states, and spin polarization of 10 possible atomic terminations in the Ti₂CoAl/MgO(100) heterojunction were comprehensively investigated using first-principle calculations. In the equilibrium interface structures, the length of the alloy–Mg bond was found to be much longer than that of the alloy–O bond because of the forceful repulsion interactions between the Heusler interface atoms and Mg atoms. The competition among d-electronic hybridization, d-electronic localization, and the moving effect of the interface metal atoms played an important role in the interface atomic magnetic moment. Unexpected interface states appeared in the half-metallic gap for all terminations. The “ideal” half-metallicity observed in the bulk had been destroyed. In TiAl–Mg and AlAl–O terminations, the maximal spin polarization of about 65% could be reserved. The tunnel magnetoresistance (TMR) value was deduced to be lower than 150% in the Ti₂CoAl/MgO(100) heterojunction at low temperature.

The geometrical structure, stability, electronic properties, and hydrogen storage capabilities of a titanium-doped B₇ cluster was calculated using density functional theory computations. The results show that the TiB₇ cluster is predicted to be stable under near-ambient conditions based on an ab initio molecular dynamic simulation. The transition state analysis found that the H₂ molecule can dissociate on the TIB₇ cluster surface to form a hydride cluster. The Ti atom within the TiB₇ cluster demonstrates an impressive capacity to adsorb up to five H₂ molecules, achieving a peak hydrogen storage mass fraction of 7.5%. It is worth noting that the average adsorption energy of H₂ molecules is 0.27–0.32 eV, which shows that these configurations are suited for reversible hydrogen storage under mild temperature and pressure regimes. In addition, calculations found that both polarization and hybridization mechanisms play pivotal roles in facilitating the adsorption of H₂ molecules onto the TiB₇ cluster. Our research results show that the TiB₇ cluster has potential for hydrogen storage applications under near-ambient conditions.