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.