Diffusion-correlated local photoluminescence kinetics in
CH3NH3PbI3 perovskite single-crystalline particles
Chunyi Zhao,1,2Wenming Tian,2* Jing Leng,2 Rongrong Cui,2 Weifeng
Liu1*, Shengye Jin2 *
1School
of Physics and Optoelectronic Engineering, Dalian University of Technology, Dalian
116024, China;
2State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics,
Chinese Academy of Sciences, Dalian 116023, China
Synthesis of CH3NH3PbI3 Single-Crystalline Particles
Synthesis of CH3NH3I. The CH3NH3I was synthesized by mixing 61 mL of
methylamine (33 wt% in absolute ethanol) and 65 mL of HI (57 wt% in water by
weight) in a flask in an ice bath at 0 °C for 2 h with stirring. The methylammonium
iodide (CH3NH3I) was achieved as the solvent was carefully removed using a rotate
evaporator (Dragon Laboratory Instruments Limited RE100-PRO, China) at 50 °C.
The white CH3NH3I powder was washed with diethyl ether three times. The final
product was collected by filtration and dried at 80 °C in a vacuum oven for 24 h.
Growth of CH3NH3PbI3 Single-Crystalline Particles. To synthesis MAPbI3
single-crystalline
particles,
we
dropcasted
200
mg/mL
PbAc2·3H2O
dimethylsulfoxide (DMSO) solution on a glass slide with the mass loading of ~2
mg/cm2, and dried the glass slide for 30 min at 65 °C to evaporating off the solvent.
We then immersed the PbAc2 glass slide in a 30 mg/mL CH3NH3I isopropanol
solution for ~24 h at room temperature. After reaction, the sample was rinsed with
isopropanol to remove the residual salt on the film, and then dried under a stream of
nitrogen flow.
1
Fig. S1 a Emission spectrum of MAPbI3 single-crystalline particles. The excitation
wavelength is 580 nm. b, c SEM images of MAPbI3 single-crystalline nanoplate and
nanowire
2
Fig. S2 Schematic presentation of a FLIM setup. Excitation of the sample is achieved
with a supercontinuum white-light laser (SC400-PP, Fianium, UK) of 680 nm
wavelength, 1 MHz repetition rate and ~6 ps pulse width. Each scanning contains
(256×256) pixels with the laser dwell time of 2.1 μs at each pixel. The laser intensity
at samples is adjusted by a neutral density filter and measured with a power meter
(PM100D S130VC, Thorlabs, USA). The fluorescence signal is collected using a high
speed detector (HPM-100-50, Hamamatsu, Japan) with a 710 nm long pass filter and
(800±40) nm band pass filter. For lifetime imaging analysis, the software SPC Image
(B&H) is used. Steady-state fluorescence emission spectra are carried out with a
monochromator (SpectraPro-2300i, Acton Research Co., USA) and an intensified
charge coupled device (ICCD) camera (PI-MAX:1024HB, USA) coupled to the back
port of the microscope, sharing the same excitation source and microscope objective
for signal collection
3
Fig. S3 Optical and PL lifetime images under different excitation intensities for
additional MAPbI3 single-crystalline particles. The excitation powers are measured as
per pulse.
Table S1 The fitting parameters with a bi-exponential function for the decays shown
in Fig. 2c. The average lifetimes are calculated by τave. = A1τ1+A2τ2.
A1
τ1
A2
τ2
τave.
1-center
45%
<7.0
55%
~300
168
2-corner
92%
~8.0
8%
~300
31
1-center
39%
<6.0
61%
~700
430
2-corner
78%
~7.8
22%
~700
154
Sample
Flat-rectangular
Flat-rod
4
Fig. S4 PL lifetime images of a MAPbI3 single-crystalline particle before (a) and after
(b) the treatment withthiophene
5
Fig. S5 Simulated diffusion processes of charge carriers in a flat square (5 μm×6 μm,
upper panels) and a flat rod (1 μm×5 μm, lower panels) MAPbI3 single-crystalline
particles at different positions (red spots) after a single pulse excitation. The diffusion
process is calculated based on Fick’s Law with a carrier diffusion coefficient D=100
μm2/μs in two-dimension. The diffusion equation is:
  2

 2 
 D 2  2   f(x ,y ,t )
t
y 
 x
ɸ is the carrier density; x and y are the position in the particle; t is time. We assume
that carriers are not quenched by the surface of particles. The initial distribution of
carriers at t =0 ns (red spots) follows a Gaussian distribution with a radius of 461 nm
according to the excitation wavelength of 680 nm (diffraction-limited optical radius r
=1.22 × λexc/2/N.A. (N.A., numerical aperture=0.9). The lifetime imaging
measurement using a confocal microscope only collects photons from the
diffraction-limited optical spot. The black dash line circles indicate the area where the
carrier density is calculated for the plots in Fig. 4a. The radius of the circle is ~476 nm
according to the emission wavelength of the MAPbI3 single-crystalline particles
6
Fig. S6 Setup for PL imaging measurement with a homogeneous wide-field
illumination configuration. The excitation area is about 20 μm in diameter
7