《Advanced Energy Materials(IF>29.698 )》Huaqiao University College of Materials Science and Engineering Zhanhua Wei Professor Team - Non-halogen surface passivating agent inhibits calcium titanate solar cell interface defects, high efficiency 24.75% and stability are realized
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Highlights
- The research team synthesized the non-halide ionic salt 1-naphthylmethylammonium formate (NMACOOH) to inhibit the formation of 2D perovskite on the surface of perovskite films.
- NMACOOH greatly suppressed interfacial non-radiative recombination by passivating cation vacancies in perovskite and metallic Pb0 and halide vacancies.
- Perovskite solar cells achieved an open-circuit voltage of 1.19 V and efficiency of 24.75% with excellent long-term stability.
(The instruments used in this study are from Enlitech: SS-PST100R
AM1.5G Spectrum Adjustable Solar Simulator, and Quantum Efficiency Measurement System QE-R.))
Background
Non-radiative recombination at the interfaces of perovskite solar cells (PSCs) is a crucial issue limiting device efficiency and stability. State-of-the-art surface passivation strategies usually use alkyl ammonium halides, but their high reactivity leads to 2D perovskite formation under working conditions, restricting the passivation effect and charge transport of PSCs.
Results
The research team synthesized 1-naphthylmethylammonium formate (NMACOOH) for surface passivation of perovskite films. Unlike traditional 1-naphthylmethylammonium iodide, NMACOOH treatment inhibited 2D perovskite formation and generated a thermally stable PbI2-NMACOOH adduct on the perovskite surface. Characterizations revealed NMA+ passivated cation vacancies in 3D perovskite, while HCOO- passivated metallic Pb0 and halide vacancies. Thus non-radiative recombination in PSCs was dramatically suppressed, achieving an open-circuit voltage of 1.19 V. Finally, PSCs with 24.75% efficiency and improved long-term stability (98% of initial efficiency after 1800 h storage) were obtained. Moreover, NMACOOH-passivated devices retained 83% of initial efficiency after working for 658 h under continuous one-sun illumination.
Methods
- The research team designed and synthesized NMACOOH as the perovskite surface passivation agent.
- Perovskite films were spin-coated on ZnO electrodes and then dipped in the NMACOOH solution for surface modification.
- XPS, FTIR etc were used to characterize the chemical structure and composition changes of perovskite films before and after NMACOOH treatment.
- Perovskite solar cell devices were fabricated and J-V curves were measured to obtain photovoltaic parameters.
- Interface trap density changes were studied by thermal admittance spectroscopy, tunneling atomic force microscopy etc.
- Long-term stability tests of PSCs were performed by prolonged storage and light soaking.
Conclusions
This work synthesized NMACOOH as the surface passivating agent for perovskite films, which inhibited 2D perovskite formation and significantly reduced interface trap density by passivating perovskite defects. An open-circuit voltage of 1.19 V and efficiency of 24.75% were achieved in perovskite solar cells with excellent long-term stability. This work provides new insights into constructing high-performance perovskite solar cells.
Figure S3. a) XRD patterns of the control, NMAI-treated, and NMACOOH-treated
perovskite films. The inset shows an enlarged view in the region from 12.4° to 13° . b)
An enlarged view in the region from 3° to 10° of a). c) GIWAXS patterns of the control,
NMAI-treated, and NMACOOH-treated perovskite films. d) an enlarged view of the
0.2 Å to 0.8 Å region. e) XRD patterns of the NMAI-treated perovskite film, the
(NMA)2PbI4 film, and the NMAI salt film. f) an enlarged view of the 3 to 12° region of
e.
Figure S7. XRD patterns of the films were prepared by varying the molar ratio between
Figure S9. a) Line-cut data as a function of azimuth angle (Azi.) extracted from the q=
0.415° ring of GIWAXS patterns of the control and NMACOOH-treated perovskite film.
b) Line-cut data as a function of azimuth angle (Azi.) extracted from q= 0.450° ring of
GIWAXS patterns of the control and NMAI-treated perovskite film.
Figure S11. Pb 4f XPS spectra of perovskite films with/without NMAI
Figure S13. J-V curves of the champion control, NMACOOH-treated and NMAItreated devices.
