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.com
Volume 7
Innovative Energy & Research
ISSN: 2576-1463
Advanced Energy Materials 2018
August 13-14, 2018
August 13-14, 2018 | Dublin, Ireland
20
th
International Conference on
Advanced Energy Materials and Research
Innov Ener Res 2018, Volume 7
DOI: 10.4172/2576-1463-C1-003
Insights into the dynamic interplay betweenmobile ions andphotovoltaic performance of organometal
halide perovskites
Byungwoo Park
Seoul National University, South Korea
A
mong various photovoltaic energy conversion systems, organometal halide perovskite (OHP) has gathered much attention
over the past few years, as the OHP-based solar cells have demonstrated high power conversion efficiency (> 22%) and
long-term stability. However, the mixed ionic/electronic conducting nature of OHPs allows the migration of mobile ionic
species (vacancy and/or interstitial defects) during solar cell operation, which is pinpointed as the major cause of anomalous
current-voltage (J-V) hysteresis. The timescales of ion diffusion span the range between sub-second to more than a minute, and
are highly dependent on the types of ions and OHPs’ nanostructures. Such ion diffusion, in combination with electron-hole
recombination, results in the complex time-dependent temporal evolution of photovoltage and photocurrent, emphasizing
the importance of frequency- and time- dependent responses of solar cells to enable high photovoltaic performance. Herein,
the photovoltaic performance of solar cells based on (FAPbI
3
)
0.83
(MAPbBr
3
)
0.17
and Cs-doped one (FA stands for (NH
2
)
2
CH
+
,
and MA for CH
3
NH
3
+
) was addressed utilizing various analysis methods such as impedance spectroscopy, transient voltage
and current measurements coupled with light/bias control (e.g., photovoltage rise, open-circuit voltage decay, photocurrent
profile, etc.) to reveal the influence of mobile ions on the photovoltaic performance.The variations of OHPs’ properties in
microscopic scale were rationally minimized (such as grain size, crystallographic orientation, crystallinity, etc.) by minimally
changing the processing parameter (e.g., annealing time) to reduce their influences on the photovoltaic performance, thereby
distinguishing the role of nanoscale defects. Nanoscopic analyses utilizing noise spectroscopy were conducted to comprehend
the effects of mobile ions on the electronic traps and thereby the photocurrent behaviors. These analyses strongly suggest that
the time-dependent photocurrent and/or photovoltage behavior are strongly correlated to the nanoscale ionic defects and their
migrations, providing deeper understanding of the operation of OHP-based solar cells.
byungwoo@snu.ac.kr