CHEM01200604009 Sreejith Kaniyankandy - Homi Bhabha ...

shell). This clearly indicated that charge transfer takes place much faster than cooling and
trapping which is immensely beneficial charge separation.
CHAPTER 6: CHARGE SEPARATION IN CdTe DECORATED GRAPHENE
In this chapter we investigate how one can manipulate relaxation dynamics in QDs by
decorating it on a metal. This study is particularly useful as metals have large density of
acceptor states which enable an efficient and fast charge separation. The system we have
investigated is chemically synthesized reduced graphene oxide decorated with CdTe QDs.
Synthesis of QDs were accomplished by colloidal methods in presence of reduced graphene
oxide. Formation of heterostructure is verified by transmission electron microscopy. Strong
interaction between CdTe and graphene was confirmed by photophysical studies.
Furthermore, we have unraveled how graphene affect dynamics by femtosecond transient
absorption study by monitoring bleach recovery kinetics of CdTe quantum dots. These
dynamics were also compared with free QDs and reduced graphene. These studies clearly
indicate an efficient that charge separation of G-CdTe composite materials.
CHAPTER 7: SUMMARY AND OUTLOOK
Aim of the thesis was to investigate not only relaxations dynamics in QDs and
heterostructures based on QDs but also to look for ways to improve on QDs. One of the
obvious ways a quantum dot has been utilized is by varying its size which helps in tuning
absorption in visible region, but does this modification itself result in an improvement of
efficiency for applications like photovoltaics. In the present thesis we demonstrate several
ways by which better charge separation can be achieved. The study of charge relaxation
dynamics helped us understand charge relaxation in heterostructure better. Such
manipulation of nanostructure showed that there is still lot of scope for improving on QD
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