Relevance of processing parameters for grain growth of metal-halide perovskites with nanoimprint

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Supporting Information

for manuscript

Relevance of processing parameters for grain growth of metal-halide perovskites with nanoimprint

Andre Mayer¹, Tobias Haeger², Manuel Runkel², Johannes Rond¹, Johannes Staabs¹, Frederic van gen Hassend³, Arne Röttger³, Patrick Görrn^1,5, Thomas Riedl^2,5,

Hella-Christin Scheer⁴

1 Chair of Large Area Optoelectronics, School of Electrical, Information and Media Engineering, University of Wuppertal, Rainer-Gruenter-Str. 21, 42119 Wuppertal, Germany

2 Chair of Electronic Devices, School of Electrical, Information and Media Engineering, University of Wuppertal, Rainer-Gruenter-Str. 21, 42119 Wuppertal, Germany

3 Chair for Novel Manufacturing Technologies and Materials, University of Wuppertal, Bahnhofstr. 15, 42651 Solingen, Germany

4 School of Electrical, Information and Media Engineering, University of Wuppertal, Rainer-Gruenter-Str. 21, 42119 Wuppertal, Germany

5 Wuppertal Center for Smart Materials & Systems, Rainer-Gruenter-Str. 21, 42119 Wuppertal, Germany

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Pristine layer:

Fig. S-1: Preparation of continuous layers of a MAPbBr3 perovskite is improved e.g. when the substrate (here Si with native oxide) is exposed with an excimer lamp (172 nm,

XERADEX 20, Radium, Germany) before spin-coating to increase the surface energy and thus to improve wetting with the precursor solution (MABr and Pb(Ac)2 in DMF). Exposure time was 60 s.

PHP process:

Fig. S-2: a) Temperature characteristics of the imprint system used for the experiments, dedicated imprint temperature here is 150°C (equivalent time: see text in section 3.2.6).

a) b)

0 5 10 15 20 25 30 160

140 120 100 80 60 40 20 0

a)

0 5 10 15 20 25 200

180 160 140 120 100 80 60 40 20 0

temperature T / °C

time t / min time t / min

imprint time equivalent time

b)

heat-up phase

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Reference experiment: (N2-anneal)

Fig. S-3: Grain size distributions obtained with annealing experiments under nitrogen.

grain size D / µm

grain size D / µm 80

60 40 20 number of grains 0

t_a= 10 min

D_m = 0.54 µm

LSD = 0.53

40 30 20 10 0

t_a = 20 min

D_m = 0.71 µm

LSD = 0.51

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2

40 30 20 10 number of grains 0

t_a= 30 min

D_m = 0.81 µm

LSD = 0.41

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2

t_a = 20s

D_m = 0.16 µm

LSD = 0.35

t_a = 30s

D_m = 0.20 µm

LSD = 0.44

0 0.1 0.2 0.3 0.4 0.5 0.6 0 0.1 0.2 0.3 0.4 0.5 0.6 20

16 12 8 4 0 20

t_a = 45s

D_m = 0.22 µm

LSD = 0.41

80 60 40 20 0

t_a = 1 min

D_m = 0.28 µm

LSD = 0.43

0 0.1 0.2 0.3 0.4 0.5 0.6 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2

t_a = 3 min

D_m = 0.44 µm

LSD = 0.44

60 50 40 30 20 10 0

t_a = 5 min

D_m = 0.46 µm

LSD = 0.42

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2

number of grains

pristine layer

D_m = 0.10 µm

LSD = 0.50

0 0.1 0.2 0.3 0.4 0.5 0.6 60

50 40 30 20 10 0

0 0.1 0.2 0.3 0.4 0.5 0.6 60

50 40 30 20 10 0

D_m = 0.14 µm

LSD = 0.39 t_a = 10s

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Fig. S-4: XRD measurements referring to annealing under nitrogen. Similar to the pristine layer the orientation is preferential, (100) / (200) only.

Fig. S-5: Grain growth according to the theoretical relationship equ. (2) (with 𝑛 = 3, as with our experiments), when a finite initial grain size exists. The regime of small times is

dominated by the initial value (here 200 nm), whereas the regime of long times (with 𝐷_! >

2𝐷_") is dominated by the exponential term.

6000

4000

2000

0

counts

2 /° (100)

(200)

15 20 25 30 35 annealing time:

prisitine 1 min 30 min

Kornwachstum mit Exponential- gesetz Exponent:

n = 3 Vorfaktor:

V = 1e13 nm V-1: Original

10⁰ 0 10¹ 10² 10³ 10⁴ 10⁵ 1000

0 mean grain size Dm / nm

time t /min

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Imprint at RT:

Fig. S-6: SEM micrographs of the pristine layer (a) and the layer imprinted at RT by a pressure of 100 bar for 5 min (b). Flattening is only observed rarely (soft-bake 125°C).

Inserts: Inclined view to illustrate topography; scale bars similar to main micrograph.

Fig. S-7: Typical AFM results of the pristine layer (a) and the layer imprinted at RT by a pressure of 100 bar for 5 min (b). The rms roughness is similar (pristine: 25 nm, imprinted 27 nm).

a) b)

180 160 140 120 100 80 60 40 20 0 204nm

240 220 200 180 160 140 120 100 80 60 40 20 251nm

0

4 µm 4 µm

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Fig. S-8: Compaction of the perovskite layer by imprint at RT (100 bar), Pb-precursor is the trihydrate Pb(Ac)2.3H2O (soft-bake 75°C, 2 min).

a) Pristine layer; b) layer after imprint at RT.

Fig. S-9: XRD characterization of layers imprinted at different pressures (RT, 5 min) compared to the respective pristine layers. All samples were prepared from the same batch (same precursor solution) subsequently. The intensities and shifts of the (100)-peak do not feature significant differences (beyond sample-to-sample variation).

a) b)

15.0 15.2 15.4

2 /°

counts

15.0 15.2 15.4

3000 2500 2000 1500 1000 500 0

2 /°

15.0 15.2 15.4

2 /°

15.0 15.2 15.4

2 /°

imprint pressure: 10bar 25bar 50bar 100bar; respective pristine layer

a) b) c) d)

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Imprint at 150°C:

Fig. S-10: Grain size distributions obtained with specific hot loading times (‘annealed’ part only).

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

80 60 40 20 0

D_m = 0.26 µm

LSD = 0.36

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

60

40

20

0

t_imp = 10s

D_m = 0.27 µm

LSD = 0.41

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

60

40

20

0

D_m = 0.30 µm

LSD = 0.41

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

50 40 30 20 10 0

t_imp = 30s

D_m = 0.34 µm

LSD = 0.39

30

20

10

0

t_imp = 1 min

D_m = 0.54 µm

LSD = 0.49

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

40 30 20 10 0

t_imp = 5 min

D_m = 0.66 µm

LSD = 0.40

t_imp = 30 min

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

80 60 40 20 0

D_m = 0.30 µm

LSD = 0.37 t_imp = 20s

t_imp= 1 day

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

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0 1 2 3 4 5 6 7 8 70

60 50 40 30 20 10 0

grain size D / µm t_imp= 1 day

D_m = 2.9 µm

LSD = 0.40

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

80 60 40 20 0

pristine layer for 10s - 1 min

D_m = 0.15 µm

LSD = 0.38

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

100 80 60 40 20 0

D_m = 0.17 µm

LSD = 0.43 pristine layer for 5 min - 1 day

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

80 60 40 20 0

t_imp = 10s

D_m = 0.27 µm

LSD = 0.39

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

60

40

20

0

t_imp = 20s

D_m = 0.29 µm

LSD = 0.38

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

60

40

20

0

t_imp = 30s

D_m = 0.28 µm

LSD = 0.40

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

50 40 30 20 10 0

t_imp = 1 min

D_m = 0.37 µm

LSD = 0.42

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

60 50 40 30 20 10 0

t_imp = 5 min

D_m = 0.45 µm

LSD = 0.39

40 30 20 10 0

t_imp = 30 min

D_m = 0.74 µm

LSD = 0.41

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

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Fig. S-12: XRD measurements comparing the ‘imprinted’ and the ‘annealed’ part of the sample (long-term experiment, 1 day; hot loading, 150°C).

Fig. S-13: Comparison of evaluated grain sizes during HL (‘imprinted’ part) with N2-anneal.

a) Overview over complete time range, b) detail of initial growth phase.

1600 1200 800 400 0

counts

2 /°

15 20 25 30 35 annealed

imprinted

PbBr₂

(100)

(200)

Regressions- analyse Daten alles:

150°C

mean grain size Dm / µm

10^-1 10⁰ 10¹ 10² 10³ 10⁴ 10

1

0

Regressions + Daten alles:

150°C SB: 125°C

N2 anneal TCI HL TCI Regr N2- TCI Regr HL TCI

0 10 20 30 40 50 60 0.5

0.4 0.3 0.2 0.1

0

time t / min time t / s

b) a)

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Fig. S-14: Driving forces for grain growth, normalized to capillary force with 100 nm grain size; red: contribution of stress due to grain growth, imprint pressure and imprint temperature (thermal stress refers to temperature differences between 25K and 125K); blue: capillary driving force due to curvature. (Parameters: pressure 100 bar, a = 6.7 10^-4/K, ggb = gs0/2 = 40 mN/m, D0 = 100nm) Linear (a) and logarithmic (b) representation.

Fig. S-15: Evaluation of activation energy from grain sizes obtained at 125°C, 150°C and 180°C. The slope indicates an activation energy of Qn = 1.19 eV.

normalized driving forces p / pcap

0 200 400 600 800 1000 2.5

2.0 1.5 1.0 0.5

0

10² 10³ 10⁴ 10¹

10⁰

10^-1

10^-2

grain size D_m / nm grain size D_m / nm

b) a)

2.2 0 2.3 2.4 2.5 100

10

1

0 (Dm)n - (D0)n

1000/T / 1/K

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Fig. S-16: Additional information with respect to characteristics of the high-purity material B.

a) SEM micrographs of the ‘annealed’ and ‘imprinted’ part, HL time 30 min

b) Grain size distribution in normalized form; merged result obtained for HL-times of 5 min to 20 min.

Simulation:

Fig. S-17: Comparison of experimental data obtained with HL and with PHP with the growth law, assuming our specific parameters (𝑇 = 150°𝐶, 𝑛 = 3.43, 𝑄_# = 1.19 𝑒𝑉). Double-log plot to emphasize differences at small times.

0 0.5 1 1.5 2 2.5 35

30 25 20 15 10 5 0

mean normalized grain size D/D_m

b)

3 µm

a) annealed hot loading

t_imp= 30min

Kornwachstum mit Exponential- gesetz Exponent:

n = 3.4 Vorfaktor:

V = 3.5e22 nm Q = 1.19 eV t-1 = 10 min

0.1 1 10 100 1

0.1 mean grain size Dm / µm

imprint time t_imp / min

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Fig. S-18: Proof of concept, that PHP experiments are well suited to determine the growth exponent n, when regarding the PHP-times after heat-up, only (here the data of the HL experiment were used for illustration). The grain size of 354 nm is used as the new ‘initial’

grain size obtained after HL for t0 = 1 min, and the time is rescaled accordingly.

a) Linear plot with initial values (nest = 3.1, Qn = 1.2 eV)

b) Logarithmic plot of a) to validate the ‘quality’ of the simulation

c) Logarithmic plot with refined exponent for exact reproduction of experiment (n = 2.8, Qn = 1.2 eV)

n aus PHP- daten (neuer Nullpunkt) Exponent:

V =7e21nm Q = 1.19 eV t-0 = 1 min d-0 = 373 nm

10^-1 10⁰ 10¹ 10² 10³ 10⁴ 10

1

0.1

V =5e20nm Q = 1.19 eV t-0 = 1 min d-0 = 373 nm

rescaled time (t - t₀)/ min

c) b)

10^-1 10⁰ 10¹ 10² 10³ 10⁴ rescaled time (t - t₀)/ min

10

1

0.1

V = 7e21 nm Q = 1.19 eV t-0 = 1 min d-0 = 373 nm

0 500 1000 1500 3.0

2.5 2.0 1.5 1.0 0.5

0

rescaled time (t - t₀)/ min

a)