Confinement Effects of a Noble Gas Dimer Inside a Fullerene Cage: Can It Be Used as an Acceptor in a DSSC?

A detailed density functional theory investigation of He-2-encapsulated fullerene C(36)and C(40)has been presented here. When confinement takes place, He-He bond length shortens and a non-covalent type of interaction exists between two He atoms. Energy decomposition analysis shows that though an attractive interaction exists in free He-2, when it is confined inside the fullerenes, repulsive interaction is observed due to the presence of dominant repulsive energy term. Fullerene C-40, with greater size, makes the incorporation of He(2)much easier than C(36)as confirmed from the study of boundary crossing barrier. In addition, we have studied the possibility of using He-2-incorporated fullerene as acceptor material in dye-sensitized solar cell (DSSC). Based on the highest energy gap, He-2@C(40)and bare C(40)fullerenes are chosen for this purpose. Dye constructed with He-2@C(40)as an acceptor has the highest light-harvesting efficiency and correspondingly will possess the maximum short circuit current as compared to pure C(40)acceptor.