Rod-shaped thiocyanate-induced abnormal band gap broadening in SCN− doped CsPbBr3 perovskite nanocrystals

Lou, Yongbing; Niu, Yandan; Yang, Dongwen; Xu, Qiaoling; Hu, Yuhang; Shen, Ying; Ming, Jing; Chen, Jinxi; Zhang, Lijun; Zhao, Yixin

doi:10.1007/s12274-017-1901-z

Cited by 53 publications

(31 citation statements)

References 41 publications

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“…S3 (Supporting Information). The sample does not show fluorescence under the ultraviolet light, and its band gap is calculated to be 4.3 eV according to its absorption edge, which is in agreement with the theoretically calculated band gap 22 . From the morphology, the average particle size is large (~20 nm), which is consistent with the increased steric hindrance caused by the rod-like structure of SCN − .…”

Section: Resultssupporting

confidence: 86%

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SCN-doped CsPbI<sub>3</sub> for Improving Stability and Photodetection Performance of Colloidal Quantum Dots

Zheng¹,

Liu²,

Bi³

et al. 2020

Acta Physico Chimica Sinica

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Inorganic halide CsPbI3 perovskite colloidal quantum dots (QDs) possess remarkable potential in photovoltaics and light-emitting devices owing to their excellent optoelectronic performance. However, the poor stability of CsPbI3 limits its practical applications. The ionic radius of SCN − (217 pm) is comparable to that of I − (220 pm), whereas it is marginally larger than that of Br − (196 pm), which increases the Goldschmidt tolerance factor of CsPbI3 and improves its structural stability. Recent studies have shown that adding SCN − in the precursor solution can enhance the crystallinity and moisture resistance of perovskite film solar cells; however, the photoelectric properties of the material post SCN − doping remain unconfirmed. To date, it has not been clarified whether SCN − doping occurs solely on the perovskite surfaces, or if it advances within their structures. In this study, we synthesized inorganic perovskite CsPbI3 QDs via a hot-injection method. Pb(SCN)2 was added to the precursor for obtaining SCN − -doped CsPbI3 (SCN-CsPbI3). X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were conducted to demonstrate the doping of SCN − ions within the perovskite structures. XRD and TEM indicated a lattice expansion within the perovskite, stemming from the large steric hindrance of the SCN − ions, along with an enhancement in the lattice stability due to the strong bonding forces between SCN − and Pb 2+ . Through XPS, we confirmed the existence of the S peak, and further affirmed that the bonding energy between Pb 2+ and SCN − was stronger than that between Pb 2+ and I − . The space charge limited current and time-resolved photoluminescence results demonstrated a decrease in the trap density of the perovskite after being doped with SCN − ; therefore, the doping process mitigated the defects of QDs, thereby increasing their optical performance, and further enhanced the bonding energy of Pb-X and crystal quality of QDs, thereby improving the stability of perovskite structure. Therefore, the photoluminescence quantum yield (PLQY) of the SCN-CsPbI3 QDs exceeded 90%, which was significantly higher than that of pristine QDs (68%). The high PLQY indicates low trap density of QDs, which is attributed to a decrease in the defects. Furthermore, the SCN-CsPbI3 QDs exhibited remarkable water-resistance performance, while maintaining 85% of their initial photoluminescence intensity under water for 4 h, whereas the undoped samples suffered complete fluorescence loss due to the phase transformations caused by water molecules. The SCN-CsPbI3 QDs photodetector measurements demonstrated a broad band range of 400-700 nm, along with a responsivity of 90 mA•W −1 and detectivity exceeding 10 11 Jones, which were considerably higher than the corresponding values of the control device (responsivity: 60 mA•W −1 and detectivity: 10 10 Jones). Finally, extending the doping of SCN − into CsPbCl3 and CsPbBr3 QDs further enhanced their optical properties on a significant scale.

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Section: Resultssupporting

confidence: 86%

“…Lou et al 22 doped SCN − into CsPbBr3, but found that the photoelectric properties of the material have not been improved. Up to now, it is not sure whether SCN − is doped into perovskite structure or concentrated on the surface of perovskites 23,24 ?…”

Section: Introductionmentioning

confidence: 99%

SCN-doped CsPbI<sub>3</sub> for Improving Stability and Photodetection Performance of Colloidal Quantum Dots

Zheng¹,

Liu²,

Bi³

et al. 2020

Acta Physico Chimica Sinica

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“…48 Pseudohalides such as SCN À (217 pm), BF 4 À (218 pm) and PF 6 À (255 pm) with a similar ionic radius to I À (220 pm) are potential candidates for improving the structural stability of APbI 3 perovskites. [49][50][51] The lone pair of electrons in SCN À ions not only has a stronger interaction with Pb 2+ than with I À , but also forms hydrogen bonds with MA. 23 The calculated formation constant for PbI 4 2À and Pb(SCN) 4 2À are 3.5 and 7, respectively, which means SCN À can improve the stability of perovskite frame structures.…”

Section: Anionsmentioning

confidence: 99%

“…We revealed that the steric shape of rodlike SCN À will induce the expansion of the CsPbBr 3 crystal lattice and increase the energy of the conduction band. 51 Fig. 2 .…”

Section: Anionsmentioning

confidence: 99%

Using steric hindrance to manipulate and stabilize metal halide perovskites for optoelectronics

Miao

Chen

et al. 2021

Chem. Sci.

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“…Salts containing thiocyanate (SCN) have been demonstrated to be able to increase grain size and reduce defects in perovskite thin film [25] and have shown beneficial effects on stability [26], device performance and suppression of hysteresis in solar cell [27]. SCN, as a kind of pseudohalide, has also presented efficient pAssivation effect on perovskite NCs [28]. For instance, Alivisatos and coworkers reported that SCN improves PLQY and stability of CBP NCs by surface pAssivation [29], and proposed a principle to pAssivate CsPbBr 3 NCs with softer, anionic and X-type Lewis bases [30].…”

Section: Introductionmentioning

confidence: 99%

Thiocyanate-Treated Perovskite-Nanocrystal-Based Light-Emitting Diodes with Insight in Efficiency Roll-Off

et al. 2020

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Light emitting diodes (LED) based on halide perovskite nanocrystals (NC) have received widespread attention in recent years. In particular, LEDs based on CsPbBr3 NCs were the object of special interest. Here, we report for the first time green LED based on CsPbBr3 NCs treated with ammonium thiocyanate solution before purification with polar solvent. The champion device fabricated based on the treated CsPbBr3 NCs showed high efficiency and high stability during operation as well as during storage. A study on morphology and current distribution of NC films under applied voltages was carried out by conductive atomic force microscopy, giving a hint on efficiency roll-off. The current work provides a facile way to treat sensitive perovskite NCs and to fabricate perovskite NC-based LED with high stability. Moreover, the results shed new light on the relation between film morphology and device performance and on the possible mechanism of efficiency roll-off in NC LED.

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Rod-shaped thiocyanate-induced abnormal band gap broadening in SCN− doped CsPbBr3 perovskite nanocrystals

Cited by 53 publications

References 41 publications

SCN-doped CsPbI<sub>3</sub> for Improving Stability and Photodetection Performance of Colloidal Quantum Dots

SCN-doped CsPbI<sub>3</sub> for Improving Stability and Photodetection Performance of Colloidal Quantum Dots

Using steric hindrance to manipulate and stabilize metal halide perovskites for optoelectronics

Thiocyanate-Treated Perovskite-Nanocrystal-Based Light-Emitting Diodes with Insight in Efficiency Roll-Off

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