Supporting Information

Transcription

1 Supporting Information Is CH 3 NH 3 PbI 3 Polar? Sharada. G 1, Pratibha Mahale 1, Bhushan P. Kore 1, Somdutta Mukherjee 1, Mysore S. Pavan 1, Chandan De 2, Somnath Ghara 2, A. Sundaresan 2, Anshu Pandey 1, Tayur. N. Guru Row 1, D. D. Sarma*,1 1 Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru , India. 2 Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru , India. S1

2 Figures: K Cooling Heating Heater power (W/g) K K K Temperature (K) Figure S1: Differential Scanning Calorimetric (DSC) curves measured for polycrystalline CH 3 NH 3 PbI 3. CH 3 NH 3 PbI 3 sample Intensity (a.u) simulated pattern θ (degree) Figure S2: Room temperature powder XRD pattern of CH 3 NH 3 PbI 3 sample (top) and the simulated pattern (bottom) using coordinates given in Ref [1] for tetragonal phase. S2

3 Measured Polarization (µc/cm 2 ) (a) Orthorhombic 77 K Electric field (kv/cm) 1 khz Measured Polarization (µc/cm 2 ) (b) Tetragonal 293 K Electric field (kv/cm) 1 khz (c) Cubic Measured Polarization (µc/cm 2 ) K 1 khz Electric field (kv/cm) Figure S3: P-E loops, typical of lossy dielectrics, measured on another sample of CH 3 NH 3 PbI 3 at (a) 77 K; (b) 293 K; and (c) 355 K. S3

4 Figure S4: Full multi-photon PL spectrum of CH 3 NH 3 PbI 3. These data are recorded at an input power of 9.2 mw using an 1800 nm pump. 800 n = 1 n = 2 n = n = 4 n = Figure S5: Fits to the multi-photon emission in the vicinity of the SHG signal region. The dashed lines represent the best fit obtained using a polynomial of degree n, as specified in each panel. Polynomials of degree between 1 and 3 evidently give a poor representation of the PL intensity in this wavelength window. While the 4 th degree polynomial (n = 4) gives a reasonable description of the tail S4

5 of the PL, while the 5 th degree one (n = 5) gives a good fit. Further, the first derivatives of these two polynomials (n = 4 and 5) are negative in the wavelength range of the SHG signal, seen for urea and quartz. For the polynomial of 4 th degree, the first derivative changes sign only at 954 nm, which is well beyond the SHG signal range; this is also indicated by the poor quality of the fit in the wavelength range beyond 954 nm for this polynomial. For the 5 th degree polynomial, however, the first derivative remains negative in the entire wavelength region considered. This implies that each fit is perfectly monotonically decreasing in the relevant range, and therefore cannot cause the spurious subtraction of the SHG signal, if any, as the latter represents a peaked structure. Residual of polynomial fit SHG peak position n = 4 n = 5 Figure S6: The residuals observed after subtracting the polynomial fit from the raw signal. For comparison, the SHG peak positions observed for urea and quartz are also marked with the arrow; it suggests that the residual, plotted above, is largely not due to any SHG. S5

6 Table S1: Single crystal XRD data. Crystal Structure data Crystal system Orthorhombic Tetragonal Cubic Space group Pnma I4/mcm Pm3 m Temperature (K) a (Å) (9) (8) (2) b (Å) (1) (8) (2) c (Å) (1) (2) (2) V (Å 3 ) (2) (2) (1) Z Radiation type Mo Kα Mo Kα Mo Kα µ (mm 1 ) Crystal size (mm) No. of measured, independent and observed [I > 2σ(I)] 3304, 3304, , 429, ,103,100 reflections R int Merged because of twinning R[F 2 > 2σ(F 2 )], wr(f 2 ), S 69, 0.243, , 0.176, , 38, 1.10 No. of parameters No. of restraints ρ max, ρ min (e Å 3 ) 5.69, , , 1.59 Table S1: Crystal structure data from single crystal XRD. S6

7 Table S2: Details of refinement of the single crystal XRD data in both non-polar and polar space groups. Crystal system Orthorhombic Tetragonal Space group Pnma Pn2 1 a I4/mcm I4cm Temperature (K) a (Å) (9) (8) b (Å) (1) (8) c (Å) (1) (2) V (Å 3 ) (2) (2) Z 4 4 Radiation type Mo Kα Mo Kα µ (mm 1 ) Crystal size (mm) No. of measured, independent and observed [I > 2σ(I)] reflections 3304, 3304, , 3304, , 429, 385 R int Merged because of twinning 89 R[F 2 > 2σ(F 2 )], wr(f 2 ), S 69, 0.243, , 0.236, , 0.176, , 811, , 0.196, 1.23 No. of parameters No. of restraints ρ max, ρ min (e Å 3 ) 5.69, , , , 5.23 Flack Parameter (8) - 0.5(1) Table S2: Details of refinement in both polar and non-polar space groups of the single crystal XRD data. In the orthorhombic structure, since the centrosymmetric space group is Pnma, the corresponding non-centrosymmetric one is Pn2 1 a.(literature reports Pna2 1.) REFERENCES (1) Kawamura, Y.; Mashiyama, H.; Hasebe, K., Structural Study on Cubic-Tetragonal Transition of CH 3 NH 3 PbI 3. J. Phys. Soc. Jpn. 2002, 71, S7