Abstract:
Methyl ammonium lead iodide has become a burgeoning class of hybrid halide perovskites of
solution-processed semiconductors. Advancements in its processing and characterization underscore
structural, optical, and electronic properties. They have led to the development of perovskite solar
cells, photo detectors, lasers, and photo diodes with power conversion efficiencies mature to be
classified as first and second-generation technologies. Characterizing forms an integral
understanding the operating principles and fundamental limitations for optoelectronics applications.
Studies outlined in this paper covers CH3NH3PbI3 using time-resolved pump-probe spectroscopy,
X-ray diffractometry, spectrophotometry and other measurements. Thus this investigatiosn may
serve as principle tool in analyzing excited state decay kinetics and optical nonlinearities in
CH3NH3PbI3 thin films. It is demonstrated herein that non-resonant photoexcitation yields a large
fraction of free carriers on a sub-picosecond time scale. If applied in practical optoelectronic
applications then any photogenerated carriers may travel long carrier lengths before they are
extracted to realize large external quantum efficiencies and efficient charge extraction. The optical
constants of CH3NH3PbI3 are interpreted using ab initio calculations through models. Findings show
good agreement between the optical constants derived from QSGW and those from related literature.
Transition from the highest valence band (VB) to the lowest conduction band (CB) was found to be
responsible for almost all the optical responses between 1.2 and 5.5 eV. It was concluded that optical
constants and energy band diagrams of CH3NH3PbI3 can be used to simulate the contributions from
different optical transitions to a typical transient absorption spectrum for many optoelectronic
applications.
