Supporting Information Passivation of PbS Quantum Dot Surface with L
Supporting Information
Passivation of PbS Quantum Dot Surface with Lglutathione in Solid-State Quantum-Dot-Sensitized Solar Cells Askhat N. Jumabekov,a Niklas Cordes,a Timothy D. Siegler,a,b Pablo Docampo,a Alesja Ivanova,a Ksenia Fominykh,a Dana D. Medina,a Laurence M. Peterc and Thomas Beina,*
a
Department of Chemistry and Center for NanoScience (CeNS), Ludwig-Maximilians-University
Munich, 81377 Munich, Germany b
Department of Chemical & Biomolecular Engineering, University of Notre Dame, Notre Dame,
Indiana 46556, United States c
Department of Chemistry, University of Bath, Bath, BA2 7AY, U.K.
Corresponding Author *Email: [email protected]
1
Preparation of TiO2 Blocking Layer. The patterned fluorine-doped tin oxide (FTO) glass substrates (1.5×2 cm2) were placed on a hot plate and partially covered with microscope glass slides to ensure the selective application of the TiO2 blocking layer (BL). The hot plate was heated to 450 °C for 30 min and then precursor solution was applied using an airbrush set with compressor to deposit the TiO2 BL. The BL deposition was done manually by spraying the precursor solution for 2 sec at approximately 15 cm distance above the substrates. This procedure was repeated 12 times with 10 sec interval to achieve a ~60 nm thick TiO2 BL on the substrates. After spraying, the hotplate was kept for 5 min at 450 °C and then cooled down to room temperature. A 0.2 M solution of titanium(IV)bis(acetylacetonate)-diisopropylate in isopropanol was used as precursor for the TiO2 BL.1 Preparation of Mesoporous TiO2 Electrodes. 100 µL of TiO2-paste with around 30 nm sized TiO2 nanocrystallites was spin-coated onto FTO substrates with a freshly made blocking layer. TiO2 nanoparticles (NPs) were prepared according to Baek et al.,2 and the TiO2 paste was prepared as described by Ito et al.3, 4 Briefly, for the preparation of TiO2 NPs, 2.2 mL of TiCl4 was added to 60 mL of distilled water while stirring and the pH of the solution adjusted to 7 by adding dropwise 28% ammonia solution (NH4OH). The mixture was then heated at 90 °C for 1 h after which the white precipitate was filtered and washed with destilled water. Then 100 mL of H2O2 was added to the precipitate and the suspension was stirred for 9 h at 100 °C. Afterwards, the mixture was transferred into a Teflon autoclave and heated for 24 h at 230 °C. The resulting TiO2 NPs were filtered and redispersed and washed with 10 mL of ethanol/H2O (1:1) and isolated via centrifugation at 1000 rpm. For the preparation of the TiO2 paste, 0.69 g TiO2 NPs was mixed with two types of ethyl cellulose (EC) (3.05 g of EC46070 (10 wt.% in ethanol) and 2.06 g of EC46080 (10 wt.% in ethanol) and 6 g of terpineol. The mixture was sonicated and stirred for 30 min each with an ultrasonic horn and a hand-held mixer (Turrax) correspondingly. This last step was repeated three times to obtain a white viscous TiO2 paste. The coated substrates were calcined in air at 500 °C for 30 min to obtain mesoporous TiO2 electrodes. The 2
electrodes were then subjected to an additional treatment in 40 mM TiCl4 (in 20 mL vial) at 70 °C for 30 min and subsequently were calcined again in air at 500 °C for 30 min.4 Preparation of Mesoporous Al2O3 Electrodes. An Al2O3 dispersion (20 wt. % in 2-propanol) with estimated NP size of
Passivation of PbS Quantum Dot Surface with Lglutathione in Solid-State Quantum-Dot-Sensitized Solar Cells Askhat N. Jumabekov,a Niklas Cordes,a Timothy D. Siegler,a,b Pablo Docampo,a Alesja Ivanova,a Ksenia Fominykh,a Dana D. Medina,a Laurence M. Peterc and Thomas Beina,*
a
Department of Chemistry and Center for NanoScience (CeNS), Ludwig-Maximilians-University
Munich, 81377 Munich, Germany b
Department of Chemical & Biomolecular Engineering, University of Notre Dame, Notre Dame,
Indiana 46556, United States c
Department of Chemistry, University of Bath, Bath, BA2 7AY, U.K.
Corresponding Author *Email: [email protected]
1
Preparation of TiO2 Blocking Layer. The patterned fluorine-doped tin oxide (FTO) glass substrates (1.5×2 cm2) were placed on a hot plate and partially covered with microscope glass slides to ensure the selective application of the TiO2 blocking layer (BL). The hot plate was heated to 450 °C for 30 min and then precursor solution was applied using an airbrush set with compressor to deposit the TiO2 BL. The BL deposition was done manually by spraying the precursor solution for 2 sec at approximately 15 cm distance above the substrates. This procedure was repeated 12 times with 10 sec interval to achieve a ~60 nm thick TiO2 BL on the substrates. After spraying, the hotplate was kept for 5 min at 450 °C and then cooled down to room temperature. A 0.2 M solution of titanium(IV)bis(acetylacetonate)-diisopropylate in isopropanol was used as precursor for the TiO2 BL.1 Preparation of Mesoporous TiO2 Electrodes. 100 µL of TiO2-paste with around 30 nm sized TiO2 nanocrystallites was spin-coated onto FTO substrates with a freshly made blocking layer. TiO2 nanoparticles (NPs) were prepared according to Baek et al.,2 and the TiO2 paste was prepared as described by Ito et al.3, 4 Briefly, for the preparation of TiO2 NPs, 2.2 mL of TiCl4 was added to 60 mL of distilled water while stirring and the pH of the solution adjusted to 7 by adding dropwise 28% ammonia solution (NH4OH). The mixture was then heated at 90 °C for 1 h after which the white precipitate was filtered and washed with destilled water. Then 100 mL of H2O2 was added to the precipitate and the suspension was stirred for 9 h at 100 °C. Afterwards, the mixture was transferred into a Teflon autoclave and heated for 24 h at 230 °C. The resulting TiO2 NPs were filtered and redispersed and washed with 10 mL of ethanol/H2O (1:1) and isolated via centrifugation at 1000 rpm. For the preparation of the TiO2 paste, 0.69 g TiO2 NPs was mixed with two types of ethyl cellulose (EC) (3.05 g of EC46070 (10 wt.% in ethanol) and 2.06 g of EC46080 (10 wt.% in ethanol) and 6 g of terpineol. The mixture was sonicated and stirred for 30 min each with an ultrasonic horn and a hand-held mixer (Turrax) correspondingly. This last step was repeated three times to obtain a white viscous TiO2 paste. The coated substrates were calcined in air at 500 °C for 30 min to obtain mesoporous TiO2 electrodes. The 2
electrodes were then subjected to an additional treatment in 40 mM TiCl4 (in 20 mL vial) at 70 °C for 30 min and subsequently were calcined again in air at 500 °C for 30 min.4 Preparation of Mesoporous Al2O3 Electrodes. An Al2O3 dispersion (20 wt. % in 2-propanol) with estimated NP size of
