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Electronic Supporting Information

In Situ Preparation of Ru–N-Doped Template-Free Mesoporous

Carbons as Transparent Counter Electrode for Bifacial Dye-

Sensitized Solar Cells

M. Aftabuzzaman, Chang Ki Kim, Haoran Zhou, and Hwan Kyu Kim*

a Global GET-Future Lab & Department of Advanced Materials Chemistry, Korea

University, 2511 Sejong-ro, Sejong 339–700, Korea, E-mail: hkk777@korea.ac.kr

Electronic Supplementary Material (ESI) for Nanoscale.This journal is © The Royal Society of Chemistry 2019

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Characterization: The weight loss during the carbonization process was inspected with

Thermogravimetric analysis (TGA: N-1000 Instrument). N2 isotherms were taken at −196 °C

using a Micromeritics ASAP 2020.The transformation in functional groups throughout the

conversion from polymer to porous carbon was observed by Fourier transform infrared (FT-

IR) spectra (Jasco FT/IR-4200 infrared spectrophotometer). Field emission scanning electron

microscope (FE-SEM: S-4700 Hitachi, Japan operated at an acceleration voltage of 10 kV)

was used to study the surface morphology and a high-resolution transmission electron

microscope (HRTEM: EM 912 Omega at 120 kV) equipped with EDX. XRD patterns of the

samples were obtained from a Rigaku Smartlab diffractometer with Cu Kα radiation operated

at 40 kV and 30 mA. Raman spectra were obtained with a confocal Raman spectrometer

(Jobin Yvon HR800, Horiba) using a 632.8 nm diode laser. Chemical composition and

structure were analyzed by XPS conducted on an AXIS-OVA (Kratos) X-ray photoelectron

spectrometer using an Al Kα X-ray source operated at 150 W at a pressure of 2.6 × 10‒9 Torr.

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Table S1. Porosity properties of N-TMC and Ru-N-TMC materials.a

SamplesSBET

(m²/g)

Smicro

(m²/g)

Smeso

(m²/g)

Vtotal

(cm³/g)

Vmicro

(cm³/g)

Vmeso

(cm³/g)

Pore Size

(nm)

N-TMC 359.2 237.1 122.0 0.51 0.10 0.41 12.3

Ru-N-TMC 464.8 305.1 159.7 0.66 0.13 0.53 12.7

aSBET is the total surface area, Vtotal is the total pore volume, Vmicro is the micropore volume, and Vmeso is the mesopore

volume.

Figure S1. FT-IR spectra of the polymer and N-TMC.

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Table S2. Elemental composition of N-TMC and Ru-N-TMC samples measured by different

methods.

Figure S2. High resolution XPS spectra of (a) C 1s of N-TMC and (b) C 1s+ Ru 3d of Ru-N-

TMC.

Samples Elements XPS (at%) EDS (at%)Elemental Analysis

(EA) (wt%)

C 86.67 88.1 83.8

N 6.7 6.01 8.08N-TMC

O 6.63 5.89 11.12

C 88.08 89.5 81.64

N 3.63 3.50 4.89

O 8.29 6.8 12.29Ru-N-TMC

Ru 0.17 0.2 1.18

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Figure S3. Electronic spray technique for counter electrode (CE) fabrication.

Figure S4. (a) Schematic presentation of the symmetrical dummy cell fabricated with two

identical electrodes. (b) Randles equivalent circuit (EC) for fitting the Nyquist impedance

spectra.

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Electrochemical and photoelectrochemical characterization. EIS and Tafel

polarization measurements were performed using the VersaSTAT 3 (Version 1.31)

AMETEK. EIS spectra were measured in the frequency range of 1 × 106 to 0.1 Hz, at an open

circuit voltage of 0 V and with 10 mV AC sinusoidal signals, and then fitted using the

Zplot/Zview2 software. Tafel polarization analyses were obtained at a scan rate of 10 mV s–1.

CV experiments were performed in a three-electrode system on an Iviumstat electrochemical

workstation at different scan rates, from 25 to 200 mVs–1, in a potential range of 0 to 0.6 V. A

Pt wire and Ag/Ag+ electrode were used as the CE and reference electrode, respectively.

Photoelectrochemical measurements were performed using a 1000 W xenon light source

(Oriel, 91193), irradiating 100 mW cm–2 specific power (1 sun at AM 1.5G). The

photovoltaic characteristics (J–V curves) of the cells were determined under this condition,

biasing the cells externally from 0 V to the open-circuit voltage at a scan rate of 50 mV s–1

and measuring the generated photocurrent. The applied potential and photocurrent were

measured using a Keithley model 2400 digital source meter. The overall process was fully

automated using Wavemetrics software. The relaxing time between applied voltage and

evaluating the photocurrent for the J–V curves was fixed at 80 ms. The solar simulator was

standardized with an NREL calibrated Si solar cell (PV Measurement Inc.).

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Figure S5. Cyclic voltammetry of (a) Pt, (b) N-TMC, and (c) Ru-N-TMC CEs at different

scan rates, from 25 to 200 mV s–1.

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Figure S6. Incident photon-to-current efficiency (IPCE) spectra of DSSC devices with Pt, N-

TMC, and Ru-N-TMC counter electrodes.

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Figure S7. CV of (a) Ru-N-TMC-0.06, (b) Ru-N-TMC-0.05, and (c) Ru-N-TMC-0.04 CEs at

different scan rates, from 25 to 200 mV s–1.

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Fig. S8. The electrochemical stability test of Ru-N-TMC-0.06 counter electrode in dummy

sell for 100 CV cycles; (a) CV was performed 10 cycles at a scan rate of 50 mV s−1, and then

(b) EIS measurement was taken at zero bias potential, the process was repeated 10 times to

complete 100 cycles (inset: charge-transfer resistance (Rct) changes for Ru-N-TMC-0.06

counter electrode vs. the EIS scan number).

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Table S3. Comparison of reported transparent counter electrodes and their performance in

bifacial dye sensitised solar cells.

PCE %Counter Electrode AVTa (%) Electrolyte Sensitiser

Front RearReference

Ru-N-TMC 42.25 Co(bpy)33+/2+ SGT-021 10.13 8.64 This work

CoS1.097@N-Doped Carbon 68 I−/I3− N719 9.11 6.64 1

PtNPs I−/I3− N719 5.72 5.00 2

Pt-EtOH I−/I3− N719 7.29 5.85 4

PPy/MWCNT 65 I−/I3− N719 7.07 4.11 5

Pt crystalline I−/I3− N719 5.80 4.80 6

Carbon quantum dot (CQD) 60 I−/I3− N719 9.08 7.01 7

PANi-MoS2 I−/I3− N719 7.99 3.40 8

PEDOT/MWCNT 47 I−/I3− N719 9.07 5.62 9

Carbon black Co(bpy)33+/2+ Z907 5.44 4.41 10

PtNP-EMTE 74 I−/I3− N719 5.67 4.87 11

CuSe I−/I3− N719 7.22 5.38 12

PVP/PANI composite Polymer- I−/I3− N719 5.45 4.66 13

Ni3S4 I−/I3− N719 6.56 4.86 14

MoS2 I−/I3− N719 6.11 3.85 14

PEDOT I−/I3− N719 7.40 5.23 15

PEDOT Co(bpy)33+/2+ Y123 8.65 7.48 15

SiO2/PEDOT−PSS 70 I−/I3− N719 5.66 4.60 16

Transparent carbon I−/I3− N719 6.07 5.04 17

PANI I−/I3− N3 6.54 4.26 18

PEDOT:PSS I−/I3− N719 5.29 2.62 19

S-doped CQDs/CoSe I−/I3− N719 9.15 5.69 20

PPy I−/I3− N3 5.74 3.06 21

SWNT 78 Co(bpy)33+/2+ MK-2 4.81 4.56 22

CoSe 60 I−/I3− N719 8.30 4.63 23

RuSe I−/I3− N719 8.76 5.90 24

PANI/TiO2 I−/I3− N719 7.06 3.41 25

aAVT= average visible transmittance (from 380 nm to 750 nm)

Note: In case of other counter electrodes author’s either did not mention AVT (from 380 nm to 750

nm) value or any quantitative value.

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