Regulation of Low-dose Stannous Iso-octanoate for Two-step Prepared Sn-Pb Alloyed Perovskite Solar Cells

doi:10.15541/jim20240191

Abstract

Abstract:

In the preparation of Sn-Pb alloyed perovskite, a large amount of stannous fluoride (SnF₂) additive is often employed to inhibit the oxidation of Sn²⁺ ions. However, excessive SnF₂ deteriorates quality of the film, photoelectric conversion efficiency (PCE) and stability of the device. Therefore, the development of new antioxidants at low doses is essential to achieve high-performance Sn-Pb alloyed perovskite solar cells. In this study, a two-step process was used to prepare Sn-Pb alloyed perovskite film. In the first step, low-dose stannous iso-octanoate (SnOct₂) was introduced to replace SnF₂to inhibit the oxidation of Sn²⁺. This study showed that the additive could improve the crystallization quality of the film, and the average grain size of the film with SnOct₂ could reach 850 nm while the amount of grain boundaries was reduced. The film with the addition of SnOct₂ still contained 93.5% Sn²⁺ after storage for 7 d in the glove box. And due to the excellent oxidation resistance of SnOct₂, the device with the additional SnOct₂ had a lower defect state density, which was reduced from 7.20×10¹⁵ to 4.74×10¹⁵cm^-3, inhibiting the non-radiative recombination. In addition, SnOct₂ improved the surface energy levels of perovskite films. Finally, PCE of Sn-Pb alloyed perovskite cell supplemented with 0.030 mmol SnOct₂ reached 17.25%, superior to that of device supplemented with 0.10 mmol SnF₂ (11.63%). After storage in nitrogen for 50 d, more than 70% of initial PCE was still preserved.

Key words: Sn-Pb alloyed perovskite, solar cell, additive engineering, two-step method, stability

CLC Number:

TQ174

WANG Yu, XIONG Hao, HUANG Xiaokun, JIANG Linqin, WU Bo, LI Jiansheng, YANG Aijun. Regulation of Low-dose Stannous Iso-octanoate for Two-step Prepared Sn-Pb Alloyed Perovskite Solar Cells[J]. Journal of Inorganic Materials, 2024, 39(12): 1339-1347.

Figures/Tables 11

Fig. 1 XRD patterns of different Sn-Pb alloyed perovskite films

Fig. 2 SEM images of different Sn-Pb alloyed perovskite films (a-d) Surfaces; (e-h) Cross sections

Fig. 3 XPS spectra of PVK-0.10SF and PVK-0.030SO films (a) Sn3d; (b) I3d; Sn4+/Sn2+ ratios of (c) PVK-0.10SF and (d) PVK-0.030SO perovskite films

Fig. 4 Optical properties and energy levels of different Sn-Pb alloyed perovskite films (a) UV-VIS-NIR spectra; (b) UPS spectra; (c) Tauc plots; (d) Energy levels of VBM, CBM, and Fermi derived from the UPS spectra

Fig. 5 Photovoltaic performance and stability of PSC-0.10SF and PSC-0.030SO devices (a) Structure diagram of Sn-Pb alloyed perovskite solar cell; (b) J-V curves of the best-performance PSCs fabricated with SnF2 and SnOct2; (c) Stability of unencapsulated PSCs stored in the N2 glove box for 50 d; (d) Stability of unencapsulated PSCs stored in air for 20 d

Table S1 Average parameters of 10 Sn-Pb alloyed PSC devices with different additive

Sample	V_OC/V	J_SC/(mA·cm^-2)	FF/%	PCE/%
PSC-0.10SF	0.628±0.021	23.17±2.24	73.76±4.77	10.73±0.89
PSC-0.015SO	0.698±0.004	26.45±0.66	75.03±3.05	13.86±0.48
PSC-0.030SO	0.728±0.009	28.64±0.58	80.83±0.57	16.86±0.38
PSC-0.045SO	0.701±0.011	27.67±0.79	77.34±2.59	15.01±0.73

Fig. S1 FWHM of different Sn-Pb alloyed perovskite films

Fig. S2 Grain size distributions of different Sn-Pb alloyed perovskite films

Fig. S3 Contact angle tests of different Sn-Pb alloyed perovskite films

Fig. S4 Photovoltaic parameter distributions of different Sn-Pb alloyed PSCs (10 devices)

Fig. S5 Internal defects of different Sn-Pb alloyed perovskite films (a, b) I-V curves of FTO/SnO2/FAxMA1-xPb0.7Sn0.3InBr1-n/PCBM/Ag; (c) EIS plots; (d) Leakage current diagram

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