The exciton dissociations and charge recombinations to a triplet state in the donor−acceptor heterojunction solar cells of [2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta-[2,1-b;3,4-b]dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) blended with ten different fullerene derivatives are theoretically investigated by using electronic structure calculations together with a Marcus formula. The detailed discussions of available accuracy in the evaluation of all quantities entering the rate expression (driving force, electronic coupling, and internal and external reorganization energies) are provided. The results reveal that the exciton dissociations in most blends are barrierless reactions because the corresponding values of driving forces and reorganization energies are very close; however, the recombinations from the charge transfer states to the triplet state of PCPDTBT occur in the Marcus normal regime. The predicted rates for both the exciton dissociation and charge recombination are in quite good agreement with experimental measurements. In addition, as the triplet charge transfer states are formed, their recombination rates become two orders larger than those for the singlet ones and have orders similar to the exciton dissociations. It is thus expected that the triplet charge recombinations are dominant channels, whereas the singlet charge recombinations can be safely neglected because of quite small rates compared to exciton dissociation ones.

Emission colors can be largely tuned from blue to white to yellow, by changing the solid state from crystal to powder to film.

The radical cation of 4,10-ditert-butyl-5,9-diisopropyl-4,5,9,10-tetraazatetracyclo[6.2.2.2]-tetradecane (sBI4T(+)), as well as its substituted bis(hydrazine) radical cations, is chosen for the investigation of the electronegativity dependence of its intramolecular electron transfer. To do so, two parameters, reorganization energy and electronic coupling, are calculated with several ab initio approaches. It is found that the electronic couplings decrease with the increase of the group electronegativity while the reorganization energies do not show an explicit dependency. Furthermore, Marcus formula is employed to reveal those effect on the electron transfer rates. The predicted rates of electron transfer generally decrease with increasing group electronegativity, although not monotonically.

Triplet−triplet energy transfer (TTET) is one of the potential approaches to detect drug−drug interactions in protein environments. Here, quantum mechanism/molecular mechanics (QM/ MM), molecular dynamics (MD), and rate theories are employed to quantitatively predict the TTET rates from a drug (S)-propranolol (PPN) to (R)-cinacalcet (CIN) within the cavity of human α 1 -acid glycoprotein.The results indicate that the TTET rates from the PPN to CIN can be described by a Marcus-type theory for electron transfer. As the drugs are set into the protein cavity, the total reorganization energy is enhanced from 0.796 to 0.870 eV, and the thermal motions of drugs and protein cause dramatic electronic coupling fluctuations. However, the fluctuation effect on TTET rates can be efficiently considered by a thermally averaged electronic coupling, which is confirmed by the rate calculations obviously incorporating the non-Condon effect. Furthermore, Fermi's golden rule predicts the consistent TTET rates with experimental ones, demonstrating the importance of nuclear tunneling effect.