Assessment of Hot-Carrier Effects on Charge Separation in Type-II CdS/CdTe Heterostructured Nanorods.
Charge separation in semiconducting materials is an essential process that determines the efficiency of photovoltaic devices and photocatalysts. Herein, we report the charge-separation dynamics in type-II CdS/CdTe heterostructured nanorods revealed by femtosecond transient-absorption (TA) measurements with a broad-band white-light probe. Under selective excitation of the CdTe segment, bleaching signals at the band gap energy of CdS were clearly observed with a rise component on a subpicosecond time scale, which indicates efficient electron transfer from CdTe to CdS. The pump-energy dependence of the TA dynamics shows that hot electrons rapidly relax to the bottom of the conduction band of CdTe, and then the electrons transfer to the CdS segment.
†Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
Makoto
M
Okano
†Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.|‡Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan.
Masanori
M
Sakamoto
†Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
Toshiharu
T
Teranishi
†Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.|§Japan Science and Technology Agency, CREST, Uji, Kyoto 611-0011, Japan.
Yoshihiko
Y
Kanemitsu
carrier cooling; charge transfer; excited states; nanocrystals; transient absorption measurements; type II heterostructures