Improved carrier transport in Mn:ZnSe quantum dots sensitized La-doped nano-TiO₂ thin film*

Abstract

Mn:ZnSe/ZnS/L-Cys core-shell quantum dots (QDs) sensitized La-doped nano-TiO2 thin film (QDSTF) was prepared. X-ray photoelectron spectroscopy (XPS), nanosecond transient photovoltaic (TPV), and steady state surface photovoltaic (SPV) technologies were used for probing the photoelectron behaviors in the Mn-doped QDSTF. The results revealed that the Mn-doped QDSTF had a p-type TPV characteristic. The bottom of the conduction band of the QDs as a sensitizer was just 0.86 eV above that of the La-doped nano-TiO2 thin film, while the acceptor level of the doped Mn2+ ions was located at about 0.39 eV below and near the bottom of the conduction band of the QDs. The intensity of the SPV response of the Mn-doped QDSTF at a specific wavelength was ∼2.1 times higher than that of the undoped QDSTF. The region of the SPV response of the Mn-doped QDSTF was extended by 191 nm to almost the whole visible region as compared with the undoped QDSTF one. And the region of the TPV response of the Mn-doped QDSTF was also obviously wider than that of the undoped QDSTF. These PV characteristics of the Mn-doped QDSTF may be due to the prolonged lifetime and extended diffusion length of photogenerated free charge carriers injected into the sensitized La-doped nano-TiO2 thin film.

Deep-ultraviolet and visible dual-band photodetectors by integrating Chlorin e6 with Ga2O3

“…[1] Such electron transfer process increases the carrier concentration in the MoS 2 , leading to the enhanced photocurrent. [26] However, compared with the absorption peak of the Ce6 at 403 nm, the visible responsitvity peak red-shifts by 53 nm due to the modulation of the adjacent MoS 2 . [1] To further confirm the photon-generated carriers transfer process, PL characteristics of the pristine Ce6 and Ce6 on MoS 2 have been measured.…”