Unveiling the operation mechanism of layered perovskite solar cells

Lin, Yun; Fang, Yanjun; Zhao, Jingjing; Shao, Yuchuan; Stuard, Samuel J.; Nahid, Masrur Morshed; Ade, Harald; Wang, Qi; Shield, Jeffrey E.; Zhou, Ninghao; Moran, Andrew M.; Huang, Jinsong

doi:10.1038/s41467-019-08958-9

Cited by 235 publications

(309 citation statements)

References 37 publications

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“…The spectra from back exhibited several short‐wavelength signals of 521 nm, 581 nm, and 614 nm, in accordance to the emission peaks of 2D perovskites with n =1, 2, and 3, respectively . Combining the XRD pattern (Supporting Information, Figure S1a) and optical absorbance spectra (Supporting Information, Figure S1b), it clearly shows the phase segregation in the layered 2D perovskite films, in line with previous studies …”

Section: Resultssupporting

confidence: 88%

Cation Diffusion Guides Hybrid Halide Perovskite Crystallization during the Gel Stage

et al. 2020

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Lead halide perovskites with mixed cations/anions often suffer from phase segregation, which is detrimental to device efficiency and their long‐term stability. During perovskite film growth, the gel stage (in between liquid and crystalline) correlates to phase segregation, which has been rarely explored. Herein, cation diffusion kinetics are systematically investigated at the gel stage to develop a diffusion model obeying Fick's second law. Taking 2D layered perovskite as an example, theoretical and experimental results reveal the impact of diffusion coefficient, temperature, and gel duration on the film growth and phase formation. A homogenous 2D perovskite thin film was then fabricated without significant phase segregation. This in‐depth understanding of gel stage and relevant cation diffusion kinetics would further guide the design and processing of halide perovskites with mixed composition to meet requirements for optoelectronic applications.

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Section: Resultssupporting

confidence: 88%

Cation Diffusion Guides Hybrid Halide Perovskite Crystallization during the Gel Stage

et al. 2020

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“…[2,11,27,29] In general, there are two possibilities to arrange different-n-value nanoplates, namely, nonuniform and uniform dispersions, in quasi-2D perovskite films. [30,31] This is often called ordered dispersion of different-n-value nanoplates. For example, differentn-value nanoplates can be formed with n = 1-5 from bottom to top surface in quasi-2D perovskite films.…”

Section: Doi: 101002/adma201901240mentioning

confidence: 99%

Two‐Photon Up‐Conversion Photoluminescence Realized through Spatially Extended Gap States in Quasi‐2D Perovskite Films

Zhu

Liu

et al. 2019

Advanced Materials

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large organic ligands with the formula of A 2 A′ n−1 M n X 3n+1 . [9][10][11][12] Such 2D perovskites can demonstrate remarkable tunabilities on optical properties via controlling morphological structures by selecting different functional A/A′ molecules. [13][14][15] Through down-conversion excitation, 2D perovskites have shown efficient light emission in spontaneous [16,17] and stimulated [18,19] regimes. Recently, amplified spontaneous emission (ASE) have been reported in 2D perovskites [(NMA) 2 (FA)Pb 2 Br 7 and (NMA) 2 (FA)Pb 2 Br 1 I 6 ] with stoichiometrically tunable wavelength from visible to near-infrared spectral range (530-810 nm) with the gain coefficient as high as > 300 cm −1 under pulse laser excitation. [20] On the other hand, it has been found that the edge states can be formed in 2D perovskites with light-emitting properties below the bandgap. [21] The discovery of edge states triggers a fundamental question of whether the gap states can be introduced as a new approach to develop multi-photon up-conversion light emission in solution-processing quasi-2D perovskite films. We should note that an up-conversion ASE was indeed observed at 720 nm in inorganic 3D perovskite (CsPbI 3 ) nanoplates under the infrared pulse laser excitation of 1200 nm. [22] In this work, we explore a new approach to realize multi-photon up-conversion photoluminescence (PL) in quasi-2D perovskite [(PEA) 2 (MA) 4 Pb 5 Br 16 (n = 5)] films by directly exciting broad gap states with continuous-wave (CW) infrared photoexcitation. The broad gap states were adjusted by selecting different n values (n = 1-5) with accelerated crystallization in quasi-2D perovskite films prepared with antisolvent processing method. Here, we found that an up-conversion PL can be observed in 2D perovskite [(PEA) 2 (MA) 4 Pb 5 Br 16 (n = 5)] films under CW 980 nm excitation when broad infrared absorption is appeared between 800 and 1500 nm. To further understand the up-conversion PL under CW infrared excitation, magnetic field effects of PL (namely, magneto-PL) were used to identify whether the gap states function as spatially extended states to generate multiphoton absorption in quasi-2D perovskite films. Furthermore, polarization-dependent PL upon using linearly and circularly polarized photoexcitations was used to explore the effects of orbit-orbit interaction on multi-photon up-conversion PL under A new approach to generate a two-photon up-conversion photoluminescence (PL) by directly exciting the gap states with continuous-wave (CW) infrared photoexcitation in solution-processing quasi-2D perovskite films [(PEA) 2 (MA) 4 Pb 5 Br 16 with n = 5] is reported. Specifically, a visible PL peaked at 520 nm is observed with the quadratic power dependence by exciting the gap states with CW 980 nm laser excitation, indicating a two-photon up-conversion PL occurring in quasi-2D perovskite films. Decreasing the gap states by reducing the n value leads to a dramatic decrease in the twophoton up-conversion PL signal. This confirms that the gap states are indeed ...

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“…Steady‐state photoluminescence (PL) is measured on the same test structures from both the perovskite side (Figure c) and the glass side (Figure d). PL peaks measured from the perovskite side of the two samples (Figure c) are identical indicating same perovskite composition and bandgap at the top (60 nm [Figure S5, Supporting Information]) of the DP and SP perovskite films . However, the PL peaks different between the two samples when measured from the glass side (Figure d and S6).…”

Section: Resultsmentioning

confidence: 88%

Unveiling the Importance of Precursor Preparation for Highly Efficient and Stable Phenethylammonium‐Based Perovskite Solar Cells

et al. 2020

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For the fabrication of low‐dimensional perovskite solar cells, understanding the effect of precursor preparation on film formation is critical to achieve high‐quality perovskite film and, therefore, high efficiency in related solar devices. Herein, the two methods to prepare phenethylammonium‐based mixed perovskite precursors with the same chemical composition are reported. These methods are called 1) different phase (DP) and 2) same phase (SP) methods as the former involves the mixing of a 3D perovskite precursor with a 2D perovskite precursor, whereas the latter involves the mixing of quasi‐2D perovskite precursors. The films prepared by these methods are characterized by X‐ray diffraction, Kelvin probe force microscopy, and scanning electron microscopy, revealing different perovskite structures. The power conversion efficiency (PCE) of the champion cells by DP and SP methods reaches 19.1% and 18.9%, respectively. Results of the aging test show a dramatic improvement in the stability of SP perovskite devices maintaining 86% of its initial performance after exposure to a relative humidity (RH) 8 ± 5% for 1000 hr and over 80% of its initial PCE after continuous 1 sun illumination (including UV) at RH 70%. The new insights provided by this work are important to design perovskite precursor preparation methods for the best device performance and stability.

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Unveiling the operation mechanism of layered perovskite solar cells

Cited by 235 publications

References 37 publications

Cation Diffusion Guides Hybrid Halide Perovskite Crystallization during the Gel Stage

Cation Diffusion Guides Hybrid Halide Perovskite Crystallization during the Gel Stage

Two‐Photon Up‐Conversion Photoluminescence Realized through Spatially Extended Gap States in Quasi‐2D Perovskite Films

Unveiling the Importance of Precursor Preparation for Highly Efficient and Stable Phenethylammonium‐Based Perovskite Solar Cells

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