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SUPPLEMENTARY INFORMATIONARTICLE NUMBER: 15017 | DOI: 10.1038/NENERGY.2015.17

NATURE ENERGY | www.nature.com/natureenergy 1

A molecularly engineered hole-transporting material for efficient perovskite solar cells

Michael Saliba, Simonetta Orlandi, Taisuke Matsui, Sadig Aghazada, Marco Cavazzini, Juan-Pablo Correa-Baena, Peng Gao, Rosario Scopelliti, Edoardo Mosconi, Klaus H. Dahmen,

Filippo De Angelis, Antonio Abate, Anders Hagfeldt, Gianluca Pozzi, Michael Graetzel and Mohammad Khaja Nazeeruddin

A molecularly engineered hole-transporting material for efficient perovskite solar cells

Michael Saliba, Simonetta Orlandi, Taisuke Matsui, Sadig Aghazada, Marco Cavazzini, Juan-Pablo Correa-Baena, Peng Gao, Rosario Scopelliti, Edoardo Mosconi, Klaus H. Dahmen, Filippo De

Angelis, Antonio Abate, Anders Hagfeldt, Gianluca Pozzi, Michael Graetzel and Mohammad Khaja Nazeeruddin

Supplementary Note 1

http://dx.doi.org/10.1038/nenergy.2015.17

2 NATURE ENERGY | www.nature.com/natureenergy

SUPPLEMENTARY INFORMATION DOI: 10.1038/NENERGY.2015.17

Supplementary Figure 1. 1H NMR of FDT



SUPPLEMENTARY INFORMATIONDOI: 10.1038/NENERGY.2015.17

Supplementary Figure 2. 1H NMR of FDT (aromatic region)




Supplementary Figure 3. 13C NMR of FDT




Supplementary Figure 4. 13C NMR of FDT (aromatic region)




Supplementary Figure 5. 1H-13C HSQC of FDT




Supplementary Figure 6. ESI-QTOF (the peak at m/z+ = 805.2159 is related to the (M+Na)+ adduct.)




Supplementary Figure 7. ESI-QTOF (Calculated and experimental molecular mass distribution due

to isotope distribution.)




Supplementary Figure 8. (a) Thermogravimetric analysis (TGA) of FDT (circles) and spiroOMeTAD (squares). FDT retains 95% of its initial weight (dashed line) at 400 °C and for SpiroOMeTAD at 445 °C. (b) Differential scanning calorimetry of FDT (circles) and spiro-OMeTAD (squares). For FDT (spiro-OMeTAD), a melting temperature of 200 °C (245 °C) and a glass transition at 110 °C (120 °C) can be observed.




Supplementary Note 2 The XRD data of FDT in Figure 1c matches well with the chemical structure. This suggests that the crystal structure mimics that of Spiro-OMeTAD with half of it replaced by planar cyclopentadithiophene (CPDT)1. The central tetrahedral sp3 hybridized carbon induce a spiro conformation out of the two orthogonally interconnected moieties, the dihedral angle of which is measured to be 85.68 o. This value is slightly smaller than that of spiro-OMeTAD (89.94 o) due to the decreased steric hindrance of the unsubstituted CPDT. (Figure SX) This effect is also reflected in the close face to face intermolecular distance (4 ) which is within the limit of - interactions as indicated by the blue dashed line2. The face to face distance between to upper half of the molecules is measured to be 5.47 In contrast, due to the highly sterically hindered geometry, no direct face to face contacts is observed from spiro-OMeTAD crystals which was reported by Ganesan and co-workers1. FDT was found to crystallize in the triclinic space group P-1 (2).

Supplementary Figure 9. The diffraction data of FDT were measured at low temperature [100(2) K] using Mo Ka radiation on a Bruker APEX II CCD diffractometer equipped with a kappa geometry goniometer. The dataset was reduced by EvalCCD3 and then corrected for absorption4. The crystal structure was solved and refined by SHELX5. The crystal structure was refined using full-matrix leastsquares based on F2 with all non hydrogen atoms anisotropically defined. Hydrogen atoms were placed in calculated positions by means of the “riding” model.

Pseudo merohedral twinning was found in the last stages of refinement and treated by the TWINROTMAT algorithm of PLATON6, obtaining one BASF value: 0.511(5). A summary of the crystallographic data, the data collection parameters, and the refinement parameters are given in Supplementary Table 1.




Supplementary Figure 10. Dihedral angle between the two planar moieties of FDT.




Supplementary Table 1. Crystallographic parameters of FDT and spiro-OMeTAD

FDT spiro-OMeTAD5

Empirical formula C49H38N2O4S2 C81H68N4O8

Formula weight 782.93 1225.455

Crystal color, habit Colorless, needle Colorless, needle

Crystal system triclinic triclinic

a, Å 6.4381(5) 13.1111(7)

b, Å 16.2215(11) 16.1465(7)

c, Å 20.3841(19) 16.9214(9)

, deg 98.191(6) 75.200(4)

, deg 96.956(7) 85.670(4)

, deg 94.165(5) 75.891(4)

V, Å3 2082.83(29) 3358.57

calc, g/cm3 1.24831 1.267

Space group P -1 P -1

Z value 2 2

Temperature, K 100 (2) 140

no. of reflections measured 9254 23601

no. of variables 519 909

Residuals: R; wR2 0.1352, 0.3381 0.0419, 0.1068




Supplementary Figure 11. Perspective views of FDT along different axis and the S-S short contacts.




Voltage (V)

Supplementary Figure 12. Best performing current-voltage scans collected under AM 1.5 simulated sunlight for FDT (open circles) and spiro-OMeTAD (solid squares) on mixed perovskite, MAPbI3 and MAPbBr3. The extracted performance parameters are presented in Supplementary Table 2. The voltage scan rate was 10 mV s-1 and no device preconditioning, such as light soaking or forward voltage bias applied for a long time, was applied before starting the measurement. The full hysteresis loop (forward and backward scan) for each scan is listed in Supplementary Table 3.




Supplementary Table 2. Short circuit current-density (Jsc), open-circuit voltage (Voc), fill factor (FF) and power conversion efficiency (PCE) of the best performing FDT and spiro-OMeTAD device with mixed perovskite, MAPbI3 and MAPbBr3 as extracted from Supplementary Figure 12. Devices were masked with a metal aperture of 0.16 cm2 to define the active area. No device preconditioning, such as light soaking or forward voltage bias applied for long time, was applied before starting the measurement.

HTM perovskite Jsc

(mA cm-2) Voc

(mV) FF

PCE (%)

Light Intensity (mW cm-2)

FDT mixed 22.7 1148 0.76 20.2 98.3

spiro 22.3 1132 0.77 19.7 98.3

FDT MAPbI3 20.6 1134 0.78 18.4 99.1

spiro 21.0 1109 0.76 17.9 98.5

FDT MAPbBr3 5.2 1355 0.79 5.6 99.7

spiro 4.4 1320 0.75 4.4 101.1




Supplementary Table 3. Short circuit current-density (Jsc), open-circuit voltage (Voc), fill factor (FF) and power conversion efficiency (PCE) of the best performing FDT and spiro-OMeTAD device on mixed perovskite, MAPbI3 and MAPbBr3 as extracted from Supplementary Figure 12 (full hysteresis loop). The curves were recorded at a scanning rate of 10 mV s−1 from forward bias (FB) to the short circuit condition (SC), and the other way around. Devices were masked with a metal aperture of 0.16 cm2 to define the active area. No device preconditioning, such as light soaking or forward voltage bias applied for long time, was applied before starting the measurement.

HTM/perovskite Scan direction Jsc (mA cm-2) Voc (mV) FF PCE (%)

FDT/mixed FB to SC 22.7 1148 0.76 20.2

SC to FB 22.2 1120 0.75 19.0

spiro/mixed FB to SC 22.3 1132 0.77 19.7

SC to FB 22.3 1130 0.72 18.2

FDT/MAPbI3 FB to SC 20.6 1134 0.78 18.4

SC to FB 20.6 1122 0.77 18.1

spiro/MAPbI3 FB to SC 21.0 1109 0.76 17.9

SC to FB 21.0 1090 0.78 18.0

FDT/MAPbBr3 FB to SC 5.2 1355 0.79 5.6

SC to FB 5.3 1325 0.71 5.0

spiro/MAPbBr3 FB to SC 4.4 1320 0.75 4.4

SC to FB 4.4 1320 0.72 4.1




Supplementary Figure 13. Device statistics of FDT and spiro-OMeTAD devices of at least 41

devices.




Supplementary Figure 14. Performance parameters of FDT and spiro-OMeTAD devices measured

after 60 days. Solar cells were stored under dry conditions.




Supplementary Note 3 The lab synthesis costs of FDT were estimated on the base of a model originally proposed by Osedach et al.7 Such a model has been recently applied by Petrus et al to the synthesis of other hole transporting materials.8

For every synthetic step the actual amounts of reactants, catalysts, reagents, solvents and materials for workup and purification required to obtain 1 gram of FDT are reported (Tables S4, S5 and S6). However, the use of 1 g of drying agent (MgSO4) was assumed to be required to obtain 1 g of the (intermediate) product.

The price per kg of the commercially available chemicals and the cost per kg of the home-made intermediates 2,7-dibromo-9H-fluoren-9-one and bis(4-methoxyphenyl)amine were multiplied by the quantities that are required for the synthesis. The costs thus obtained were summed up affording an estimation of the direct material cost for FDT (34.43 €/g = 38.85 $/g, Table S4), in analogy with what was reported in the literature.7,8

However, since this figure does not take into account several important parameters (e.g. energy consumption, waste treatment and labor), it was multiplied by a factor of 1.5 to get a more realistic estimation of lab synthesis costs of ~60 $/g as reported in the main text (38.85 x 1.5 = 58.30 $/g).




Supplementary Table 4. Materials quantities and cost for the synthesis of FDT.a

Chemical Weight reagent

(g/g)

Weight solvent (g/g)

Weight workup

(g/g)

Price of Chemical

(€/kg)

Chemical cost (€/g product)

Cost per step (€/step)

2,3-Dibromothiophene 1.11 1900.00 2.11 2-Bromothiophene 0.82 350.00 0.29 Mg 0.20 59.00 0.01 Pd(dppf)2Cl2 0.03 22760.00 0.76 Et2O 9 20.27 0.18 Et2O 18.00 20.27 0.36 MgSO4

1.01

48.04

0.05

3.76

3-Bromo-2,2'-bithiophene 1.01 NBS 1.47 135.50 0.20 AcOH 7 35.53 0.03 CHCl3 16 2.30 0.04 CH2Cl2 40.00 9.88 0.40 NaHCO3 10.00 42.50 0.43 MgSO4 1.53 48.04 0.07 Petroleum ether

25.00

12.36

0.31

1.48

3,5,5'-Tribromo-2,2'bithiophene

1.53

Chlorotrimethylsilane 0.87 54.50 0.05 n-BuLi (1.6M solution) 3.12 128.40 0.43 Et2O 20 20.27 0.41 Et2O 43.00 20.27 0.89 MgSO4 1.12 48.04 0.05 Hexanes 300.00 6.01 1.80 Silica gel

50.00

21.19

1.06

4.69

3-Bromo-5,5'bis(trimethylsilyl)-2,2'bithiophene (1)

1.12

2,7-dibromo-9H-fluoren-9one

0.81 391.35 0.32 b

n-BuLi (1.6M solution) 1.23 128.40 0.16 THF 20 8.80 0.18 Et2O 26 20.27 0.53 NH4Cl 1.40 50.40 0.07 MgSO4 1.25 48.04 0.06 Petroleum ether 286.00 12.36 3.53 CH2Cl2 66.00 9.88 0.65 Silica gel

65.00

21.19

1.37

6.87




9-(5,5'-Bis(trimethylsilyl)- [2,2'-bithiophen]-3-yl)2,7-dibromo-9H-fluoren9-ol (2)

1.25

FeCl3 0.16 15.13 0.00 CHCl3 c 166 d 21.51 3.57 Petroleum ether 175.00 12.36 2.16 CHCl3 45.00 2.30 0.10 Silica gel

50.00

21.19

1.06

6.89

2',7'-Dibromospiro [cyclopenta [2,1-b:3,4b']dithiophene-4,9'fluorene] (3)

0.76

Bis(4-methoxy phenyl)amine

0.79 6860.00 5.42 e

tBu3P (1M solution) 0.05 9070.80 0.49 Pd2(dba)3 0.06 14980.00 0.83 NaOtBu 0.37 324.00 0.12 Toluene 11.00 3.61 0.04 Et2O 35.00 20.27 0.71 MgSO4 1.00 48.04 0.05 Hexanes 210.00 6.01 1.26 AcOEt 72.00 3.21 0.23 Silica gel

75.00

21.19

1.59

10.74

Total 11.09 275 1572.31 34.43

a See Supplementary Note 1

b See Supplementary Table 5

c Stabilized with amylene. The solvent recovered by evaporation under reduced pressure has been reused in more than five subsequent runs affording constant yields of product 3.

d 372.5 g of solvent has been used to produce 1.70 g of 3 in five subsequents cyclization runs, each one performed on 0.56 g of starting material 2.

e See Supplementary Table 6




Supplementary Table 5. Materials quantities and cost for the synthesis of 2,7-dibromo-9H-fluoren-9one.9


(g/g)


Weight workup

(g/g)

Price of Chemical

(€/kg)



Fluoren-9-one 0.62 371.00 0.23 Br2 1.21 56.64 0.07 H2O 3 - - MeOH

10

1.96

0.02

0.32

Total 1.83 3 10 0.32




Supplementary Table 6. Materials quantities and cost for the synthesis of bis(4methoxyphenyl)amine.9


(g/g)


Weight workup

(g/g)

Price of Chemical

(€/kg)



1-Iodo-4methoxybenzene

2.54 665.00 1.69

tert-Butyl carbamate 0.51 24.95 1.27 CuI 0.17 254.00 0.04 K3PO4 5.52 70.00 0.39 N1,N2-Dimethylethane1,2-diamine

0.19 8320.00 1.58

Toluene 13.00 3.61 0.05 Toluene 4.50 3.61 0.02 MgSO4 1.13 48.04 0.05 Petroleum ether 1.30 12.36 0.02 5.11 tert-Butyl bis(4methoxyphenyl) carbamate

1.13

CF3COOH

1.47

135.50

0.31

0.31

Total 10.40 13 6.93 5.42




Supplementary References

1 Ganesan, P. et al. A simple spiro-type hole transporting material for efficient perovskite solar cells. Energ Environ Sci 8, 1986-1991, (2015).

2 Avasthi, K., Shukla, L., Kant, R. & Ravikumar, K. Folded conformations due to arene interactions in dissymmetric and symmetric butylidene-linker models based on pyrazolo[3,4d]pyrimidine, purine and 7-deazapurine. Acta crystallographica. Section C, Structural chemistry 70, 555-561, (2014).

3 Duisenberg, A. J. M., Kroon-Batenburg, L. M. J. & Schreurs, A. M. M. An intensity evaluation method: EVAL-14. J Appl Crystallogr 36, 220-229, (2003).

4 Blessing, R. H. An Empirical Correction for Absorption Anisotropy. Acta Crystallogr A 51, 3338, (1995).

5 Sheldrick, G. M. A short history of SHELX. Acta Crystallogr A 64, 112-122, (2008). 6 Spek, A. L. Structure validation in chemical crystallography. Acta Crystallogr D 65, 148-155,

(2009). 7 Osedach, T. P., Andrew, T. L. & Bulovic, V. Effect of synthetic accessibility on the commercial

viability of organic photovoltaics. Energ Environ Sci 6, 711-718, (2013). 8 Petrus, M. L., Bein, T., Dingemans, T. J. & Docampo, P. A low cost azomethine-based hole

transporting material for perovskite photovoltaics. J Mater Chem A 3, 12159-12162, (2015). 9 Zhang, X., Han, J. B., Li, P. F., Ji, X. & Zhang, Z. Improved, Highly Efficient, and Green Synthesis

of Bromofluorenones and Nitrofluorenones in Water. Synthetic Commun 39, 3804-3815, (2009).


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