High LUMO Level Enhances Open-Circuit Voltage and Efficiency

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Supporting information of

Indene−C60 Bisadduct Electron Transporting Material with the

High LUMO Level Enhances Open-Circuit Voltage and Efficiency

of Tin-Based Perovskite Solar Cells

Myeongjeong Lee,†,‡_{Dawoon Kim,}†, ‡_{Yong Kyu Lee,}†,‡_{Hansol Koo,}‡_{Kyu Tae Lee,}‡_{and In}

Chung*, †, ‡

†_{Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic}

of Korea

‡_{School of Chemical and Biological Engineering, and Institute of Chemical Processes, Seoul}

National University, Seoul 08826, Republic of Korea

Corresponding Author

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Table S1. TRPL characteristics for the FA0.9PEA0.1SnI3 films without and with ETLs on a

ITO/PEDOT:PSS substrate.

Sample τ1 [ns] Ratio [%] τ2 [ns] Ratio [%] τave [ns]

Without ETL 3.1 34 10.7 66 8.1

ICBA 1.9 42 6.1 58 4.4

PCBM 1.8 48 5.8 52 3.9

C60 1.6 51 5.1 49 3.3

The PL decay curves of the samples were fitted with a bi-exponential decay model containing a fast and a slow decay processes.1-3_{We consider the fast decay process is attributed}

to the quenching of the photogenerated free carriers transporting from the perovskite layer to the PEDOT:PSS or ETLs, and the slow decay process originates from the radiative recombination of free carriers before charge collection. For the FA0.9PEA0.1SnI3 film on an

ITO/PEDOT:PSS substrate without ETL, the lifetime of fast (τ1) and slow decay (τ2) is 3.1 and

10.7 ns and the weight fraction is 34 and 66%, respectively. In addition to ETLs, PL lifetimes of the FA0.9PEA0.1SnI3 perovskite significantly decrease and the ratio of τ1 increases, showing

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Table S2. Photovoltaic parameters for FA0.9PEA0.1SnI3 solar cells with a different ETL of

ICBA, PCBM, and C60.

ETL VOC [V] JSC [mA cm2] FF [%] PCE [%]

ICBA Champion 0.651 16.88 64 7.05 Average 0.66 ± 0.01 16.16 ± 0.71 58.53 ± 1.40 6.27 ± 0.30 PCBM Champion 0.490 18.14 62 5.54 Average 0.48 ± 0.01 17.94 ± 0.63 60.91 ± 1.97 5.22 ± 0.38 C60 Champion 0.403 17.76 62 4.46 Average 0.40 ± 0.01 17.00 ± 0.88 62.12 ± 1.53 4.22 ± 0.26

The statistical data including average values standard deviations were calculated from 8 devices with a C60 and PCBM ETL, respectively, and 11 devices with an ICBA ETL.

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Table S3. Summary of photovoltaic parameters for the best performing FASnI3-based

perovskite solar cells previously reported and in this work.

Device structure ETL HTL Absorber _V_OC [V] JSC [mA cm2_] FF [%] PCE [%] Ref.

p-i-n Ag C60/BCP PEDOT:PSS FASnI3-PVA 0.632 20.37 69.3 8.92 4

p-i-n Ag C60/BCP PEDOT:PSS GAxFA1-xSnI3

-EDAI2 0.619 21.2 72.9 9.6 5

p-i-n Ag C60/BCP PEDOT:PSS FA1-xMAxSnI3 0.61 21.2 62.7 8.12 6

p-i-n Ag C60/BCP PEDOT:PSS FASnI3-EDAI2 0.583 21.3 71.8 8.9 7

p-i-n Ag PCBM NiOx FASnI3-SnCl2 0.552 17.64 69.4 6.76 8

p-i-n Ag C60/BCP PEDOT:PSS FA1-xMAxSnI3 0.55 19.4 67 7.2 9

p-i-n Ag C60/BCP

PEDOT:PSS/PTN-Br FASnI3 0.57 20.66 67.4 7.94 10 p-i-n Al PCBM PEDOT:PSS FA1-x(PEA)xSnI3

-FASCN 0.53 22.5 68.3 8.17 11 p-i-n Ag C60/BCP PEDOT:PSS FA1-x(PEA)xSnI3 0.525 24.1 71 9 12

n-i-p Au TiO2 PTAA {en}FASnI3 0.48 22.54 65.96 7.14 13

n-i-p Au TiO2 benzodithiophene {en}FASnI3 0.497 22.41 68.21 7.59 14

p-i-n Ag C60/BCP PEDOT:PSS/LiF FA1-x(PEA)xSnI3 0.47 20.07 74 6.98 15

p-i-n Al ICBA/BCP PEDOT:PSS FA0.9(PEA)0.1SnI3 0.651 16.88 64 7.05 This

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Figure S1. XRD patterns of the FA0.9PEA0.1SnI3 films deposited on an ITO/PEDOT:PSS

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Figure S2. Typical top view SEM images of (a) FASnI3 and (b) FA0.9PEA0.1SnI3 perovskite

films deposited on an ITO/PEDOT:PSS substrate, shown in various magnifications. Red dotted circles in (a) indicate pinholes typically found in FASnI3 perovskite films. FA0.9PEA0.1SnI3

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Figure S3. (a) Tauc plots and (b) TRPL decay curves for the FA0.9PEA0.1SnI3 and FASnI3 films

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Figure S4. XRD patterns of the FA0.9PEA0.1SnI3 films deposited on an ITO/PEDOT:PSS

substrate without and with a respective ICBA, PCBM, and C60 ETL. The asterisk indicates the

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Figure S5. Absorbance spectra of the FA0.9PEA0.1SnI3 film deposited on ITO/PEDOT:PSS

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Figure S6. UPS data corresponding to (a) the secondary electron onset region and (b) valence

band region of the FA0.9PEA0.1SnI3 and ETL films. The UPS measurements were carried out

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Figure S7. J-V characteristics of FA0.9PEA0.1SnI3 solar cells with a variation in a thickness of

C60. On a top of C60, a 5 nm of BCP layer is thermally deposited. We found that the optimal

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Figure S8. J-V characteristics of FA0.9PEA0.1SnI3 solar cells with a variation in a revolution

per minute (RPM) of spin-coating for PCBM. On the top of PCBM, a 5 nm of BCP layer is thermally deposited. The deposition condition of a solution-processed PCBM was optimized by controlling RPM for spin-coating, and we found that 4000 rpm is the best condition.

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Figure S9. J-V characteristics of FA0.9PEA0.1SnI3/ICBA solar cells with a variation in a RPM

of ICBA spin coating. 5 nm of BCP is thermally deposited in onto ICBA layer. The RPM of a spin-coated ICBA layer was optimized to 4000 rpm.

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Figure S10. J-V characteristics of FA0.9PEA0.1SnI3 solar cells with respective ICBA, PCBM

and C60 ETL. A BCP layer with 5 and 10 nm was tested. A 10 nm thick BCP layer reduces

photovoltaic parameters mainly due to the serious charge accumulation occurring at the interface between the ETL and BCP layer.

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Figure S11. (a) Electrical impedance spectra (EIS) and (b) dark J-V curves of the

FA0.9PEA0.1SnI3 solar cells with a respective ICBA, PCBM and C60 ETL. Inset in (a) shows the

equivalent circuit employed in the Nyquist fitting, including the series resistance (Rs), transfer

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