Fast Dissociation and Reduced Auger Recombination of Multiple Excitons in Closely Packed PbS Nanocrystal Thin Films.
Exciton decay dynamics in chemically treated PbS quantum-dot (QD) films have been studied using femtosecond transient-absorption (TA) spectroscopy. In photoconductive QD films, a decay component with a lifetime of a few nanoseconds appeared in the TA signals because of exciton dissociation under weak excitation. Increasing excitation fluence resulted in additional fast-decay components corresponding to the lifetimes of multiple excitons, which decreased with increasing photoconductivity of the closely packed QD films. Auger recombination in photoexcited QDs was suppressed in highly photoconductive films. Our findings clearly show that the carrier transfer between the QDs dominates the lifetimes of single and multiple excitons.
†Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
Taishi
T
Nishihara
†Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
Hirokazu
H
Tahara
†Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
Makoto
M
Okano
‡Frontier Core-Technology Laboratories, Fujifilm Corporation, Ashigarakami-gun, Kanagawa 258-8577, Japan.
Masashi
M
Ono
†Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.|§Japan Science and Technology Agency, CREST, Kyoto University, Uji, Kyoto 611-0011, Japan.
Yoshihiko
Y
Kanemitsu
Auger recombination; exciton dissociation; multiple exciton generation; quantum dot film; transient absorption