Spin–orbit coupling and Lorentz force enhanced efficiency of TiO2‐based dye sensitized solar cells

We report on the effect of the strong spin–orbit coupling and the Lorentz force on the efficiency of TiO2-based dye sensitized solar cells. Upon inclusion of Ho2O3, due to the strong spin–orbit coupling of the rare earth Ho3+ ion, we do see 13% enhancement in the efficiency. We attribute such an enhancement in power conversion efficiency to the increased lifetime of the photo-excited excitons. Essentially, a Ho3+ ion accelerates the phenomenon of the spin rephasing or the intersystem crossing of the excitons in a photosensitizer. Increase in the absorbance and decrease in the photoluminescence intensity suggests a decrease in the recombination rate, hinting an enhanced charge transport, and is in accordance with our electrochemical impedance spectra and the J–V characteristics. From the above we strongly believe that enhanced efficiency of the device is due to increased intersystem crossing which would accelerate the exciton dissociation. On top of spin–orbit interaction, a configuration where the electric and magnetic fields are perpendicular to each other helped in enhancing the efficiency by 16%, suggesting that the Lorentz force also plays a dominant role in controlling the charge transport of the photo-generated charge carriers. We strongly believe that this simple and novel strategy of improving the efficiency may pave the way for realizing higher efficiency dye sensitized solar cells.