Ultrafast Hole Trapping and Relaxation Dynamics in p-Type CuS Nanodisks.
CuS nanocrystals are potential materials for developing low-cost solar energy conversion devices. Understanding the underlying dynamics of photoinduced carriers in CuS nanocrystals is essential to improve their performance in these devices. In this work, we investigated the photoinduced hole dynamics in CuS nanodisks (NDs) using the combination of transient optical (OTA) and X-ray (XTA) absorption spectroscopy. OTA results show that the broad transient absorption in the visible region is attributed to the photoinduced hot and trapped holes. The hole trapping process occurs on a subpicosecond time scale, followed by carrier recombination (~100 ps). The nature of the hole trapping sites, revealed by XTA, is characteristic of S or organic ligands on the surface of CuS NDs. These results not only suggest the possibility to control the hole dynamics by tuning the surface chemistry of CuS but also represent the first time observation of hole dynamics in semiconductor nanocrystals using XTA.
†Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201, United States.
John
J
Ludwig
‡Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, State Key Laboratory of Applied Organic Chemistry and The Research Center of Biomedical Nanotechnology, Lanzhou University, Lanzhou, Gansu 730000, People's Republic of China.
Li
L
An
†Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201, United States.
Brian
B
Pattengale
§X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60349, United States.
Qingyu
Q
Kong
§X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60349, United States.
Xiaoyi
X
Zhang
‡Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, State Key Laboratory of Applied Organic Chemistry and The Research Center of Biomedical Nanotechnology, Lanzhou University, Lanzhou, Gansu 730000, People's Republic of China.
Pinxian
P
Xi
†Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201, United States.
Jier
J
Huang
CuS nanodisks; X-ray transient absorption spectroscopy; energy conversion; optical transient absorption spectroscopy