Two-step solvent post-treatment on PTAA for highly efficient and stable inverted perovskite solar cells

Yang Li; Chao Liang; Gaopeng Wang; Jielei Li; Shi Chen; Shihe Yang; Guichuan Xing; Hui Pan

doi:10.1364/PRJ.398529

Photonics Research, Volume. 8, Issue 10, A39(2020)

Two-step solvent post-treatment on PTAA for highly efficient and stable inverted perovskite solar cells

Yang Li¹, Chao Liang¹, Gaopeng Wang², Jielei Li¹, Shi Chen¹, Shihe Yang², Guichuan Xing^1,4、*, and Hui Pan^1,3,5、*

¹Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Macao SAR, 999078, China

²Guangdong Key Laboratory of Nano-Micro Material Research, School of Chemical Biology and Biotechnology, Shenzhen Graduate School, Peking University, Shenzhen 518055, China

³Department of Physics and Chemistry, Faculty of Science and Technology, University of Macau, Macao SAR, 999078, China

⁴e-mail: gcxing@um.edu.mo

⁵e-mail: huipan@um.edu.mo

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Figures & Tables(14)

Fig. 1. Transmittance of PTAA on (a) ITO glass and on (b) electronic grade pure glass; SEM (scale bar=1 μm) images of (c) ITO glass and (d) PTAA precursor covered ITO glass. XPS profiles for PTAA, PTAA+DMF, PTAA+DMF/CB, and PTAA+DMF/toluene on ITO substrate: (e) scan for O 1s; (f) scan for N 1s.

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Fig. 2. AFM phase images (500 nm×500 nm) of (a) ITO/PTAA, (b) ITO/PTAA/DMF, (c) ITO/PTAA/DMF/toluene, and (d) ITO+PTAA/DMF/CB. (Insets show the 3D morphology for each film and RMS reflects the film roughness.)

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Fig. 3. (a)–(c) Cross-sectional SEM images for devices with PTAA, PTAA/DMF/CB, and PTAA/DMF/toluene as HTLs, respectively. (d)–(h) Top-view SEM images of perovskite film on glass/PTAA, glass, glass/PTAA/DMF/toluene, glass/PTAA/DMF, and glass/PTAA/DMF/CB. (Red circles show pin holes.) (i)–(l) Contact angles for (i) PTAA; (j) PTAA/DMF; (k) PTAA/DMF/CB, and (l) PTAA+DMF/toluene on glass.

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Fig. 4. Top-view AFM images (1 μm×1 μm) of perovskites on PTAA with different solvent modification during (rotating state) or after spin coating of DMF (stable state): (a) glass/PTAA/DMF/toluene (drop under stable state)+PSK; (b) glass/PTAA/PSK; (c) glass/PTAA/DMF/toluene (drop while rotating)/PSK; (d) glass/PTAA/DMF/PSK; (e) glass+PTAA/DMF/CB (drop while rotating)/PSK; (f) glass+PTAA/DMF/CB (drop under stable state)/PSK.

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Fig. 5. (a) XRD patterns and (b) UV-vis absorption spectra for PTAA/PSK, PTAA/DMF/PSK, PTAA/DMF/CB/PSK, and PTAA/DMF/toluene/PSK on ITO substrates. (c) Steady-state PL and (d) TRPL spectra for PSCs corresponding to the films in (a) and (b).

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Fig. 6. (a) J-V curve under 1.5G sunlight through a solar simulator by reverse scan for PSCs using PTAA with different concentrations (device structure: ITO/PTAA/PSK/PCBM/BCP/Ag). (b) Best device based on toluene-treated PTAA. (c) to (g) J-V curves for devices based on different PTAA substrates by reverse and forward scans: (d) PTAA without any treatment; (e) PTAA treated with DMF; (f) PTAA treated with DMF/CB. The active area for the above cells is 0.05 cm2.

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Fig. 7. (a) Device structure. (b) Enlarged drawing of toluene between PTAA and perovskite. (c) Energy-level diagram of each layer in the device. (d) Fabrication process of PSCs based on DMF/toluene-treated PTAA. (e) J-V curves (by reverse scan) for the devices in this research. (f) Nyquist plot for PSCs with pristine PTAA and PTAA treated by DMF, DMF/CB, and DMF/toluene, respectively (bias voltage=0.6 V, frequency in range of 0.1–100 Hz). (g) IPCE curves of PSCs by using PTAA, PTAA/DMF, PTAA/DMF/CB, and PTAA/DMF/toluene as HTLs. (h) Long-term stability test for PSCs fabricated based on PTAA treated by different solvents in ambient with humidity above 35% and temperature around RT.

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Fig. 8. Data difference analysis for 36 PSCs by using toluene-treated PTAA as hole transport material in inverted structure.

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Fig. 9. Photovoltaic parameters of the best device (with DMF/toluene modified PTAA as HTL) newly prepared as well as after storage in N2-filled glove box for 10 and 20 days (measured under continuous 1.5G light illumination, 30 s once, in ambient). Relationships between exposure time and exposure time and (a) efficiency, (b) Jsc, (c) Voc, and (d) FF, respectively.

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Table 1. Film Thickness Measurement Result by a Step Profiler
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Table 1. Film Thickness Measurement Result by a Step Profiler
Group PTAA+DMF+CB+PSK PTAA+DMF+toluene+PSK PTAA+DMF+PSK PTAA
Thickness 450 nm 456 nm 459 nm 15 nm

Table 2. Contact Angle Measurement Results Corresponding to PTAA with Different Solvent Treatment^a
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Table 2. Contact Angle Measurement Results Corresponding to PTAA with Different Solvent Treatment^a
Group $θ_{(M)}$ $θ_{(L)}$ $θ_{(R)}$
PTAA 107.30 106.49 108.10
PTAA/DMF 106.80 106.68 106.92
PTAA/CB 60.48 60.91 60.04
PTAA/toluene 81.94 84.06 79.80

Table 3. TRPL Time Decay Analysis Through Double Exponential Fitting Method

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Table 3. TRPL Time Decay Analysis Through Double Exponential Fitting Method

Group	A₁	A₂	$τ_{1}$ (ns)	$τ_{2}$ (ns)	$τ_{average}$ (ns)
PTAA/DMF/CB/PSK^a	126.65	1.96	1.82	7.41	2.15
PTAA/DMF/toluene/PSK^a	211.51	2.66	1.72	5.66	1.88
PTAA/DMF/PSK	10.03	0.94	3.48	11.40	5.35
PTAA/DMF/toluene/PSK^b	236.25	1.99	1.56	8.69	1.88
PTAA/DMF/CB/PSK^b	26.54	1.56	2.61	7.72	3.37
PTAA/PSK	16.95	0.86	2.72	17.86	6.50

Table 4. Long-Term Stability for Devices with Pristine PTAA Compared with PTAA Treated by DMF, DMF/Toluene, and DMF/CB, with Different Storage Times
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Table 4. Long-Term Stability for Devices with Pristine PTAA Compared with PTAA Treated by DMF, DMF/Toluene, and DMF/CB, with Different Storage Times
Storage Time Efficiency (%)
PTAA PTAA/DMF PTAA/DMF/toluene PTAA/DMF/CB
24 h 17.20 16.86 19.31 18.78
240 h 16.84 15.95 18.78 17.88
480 h 13.29 15.65 18.24 16.37
720 h 4.79 7.05 17.07 15.00

Table 5. Photovoltaic Parameters of the Best Solar Cell with Toluene-Treated PTAA as HTL at Different Storage Times (Measured 21 Times, 30 s Once Under Continuous 1.5G Sunlight Without Encapsulation)

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Table 5. Photovoltaic Parameters of the Best Solar Cell with Toluene-Treated PTAA as HTL at Different Storage Times (Measured 21 Times, 30 s Once Under Continuous 1.5G Sunlight Without Encapsulation)

Parameters		Fresh Cells	10 Days Later	20 Days Later
FF	Average	78.00	78.60	78.94
FF	Maximum	80.11	81.64	80.65
$J_{sc}$ ( $mA / {cm}^{2}$ )	Average	23.44	21.95	20.87
$J_{sc}$ ( $mA / {cm}^{2}$ )	Maximum	23.87	23.63	22.72
Efficiency (%)	Average	18.95	17.00	15.75
Efficiency (%)	Maximum	19.51	17.68	16.17
$V_{oc}$ (V)	Average	1.02	1.00	0.96
$V_{oc}$ (V)	Maximum	1.09	1.10	0.98

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Yang Li, Chao Liang, Gaopeng Wang, Jielei Li, Shi Chen, Shihe Yang, Guichuan Xing, Hui Pan, "Two-step solvent post-treatment on PTAA for highly efficient and stable inverted perovskite solar cells," Photonics Res. 8, A39 (2020)

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Paper Information

Special Issue: PEROVSKITE PHOTONICS

Received: Jun. 2, 2020

Accepted: Jul. 13, 2020

Published Online: Sep. 18, 2020

The Author Email: Guichuan Xing (gcxing@um.edu.mo), Hui Pan (huipan@um.edu.mo)

DOI:10.1364/PRJ.398529

Topics

laser devices and laser physics

Lasers and Laser Optics

Laser physics

laser manufacturing

Instrumentation, Measurement and Metrology

Table 1. Film Thickness Measurement Result by a Step Profiler

Table 1. Film Thickness Measurement Result by a Step Profiler

Table 2. Contact Angle Measurement Results Corresponding to PTAA with Different Solvent Treatmenta

Table 2. Contact Angle Measurement Results Corresponding to PTAA with Different Solvent Treatmenta

Table 3. TRPL Time Decay Analysis Through Double Exponential Fitting Method

Table 3. TRPL Time Decay Analysis Through Double Exponential Fitting Method

Table 4. Long-Term Stability for Devices with Pristine PTAA Compared with PTAA Treated by DMF, DMF/Toluene, and DMF/CB, with Different Storage Times

Table 4. Long-Term Stability for Devices with Pristine PTAA Compared with PTAA Treated by DMF, DMF/Toluene, and DMF/CB, with Different Storage Times

Table 5. Photovoltaic Parameters of the Best Solar Cell with Toluene-Treated PTAA as HTL at Different Storage Times (Measured 21 Times, 30 s Once Under Continuous 1.5G Sunlight Without Encapsulation)

Table 5. Photovoltaic Parameters of the Best Solar Cell with Toluene-Treated PTAA as HTL at Different Storage Times (Measured 21 Times, 30 s Once Under Continuous 1.5G Sunlight Without Encapsulation)

Table 2. Contact Angle Measurement Results Corresponding to PTAA with Different Solvent Treatment^a

Table 2. Contact Angle Measurement Results Corresponding to PTAA with Different Solvent Treatment^a