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Preparation of heterostructure quantum dots towards wide-colour-gamut display
Materials Letters 254 (2019) 171–174
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
Preparation of heterostructure quantum dots towards wide-colour-gamut display Rui Cheng, Haixia Shen, Zhangchi Chen 1, Fucheng Li, Ge Li, Cai-Feng Wang ⇑, Su Chen ⇑ State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing 210009, China
a r t i c l e
i n f o
Article history: Received 11 April 2019 Received in revised form 26 June 2019 Accepted 7 July 2019 Available online 8 July 2019 Keywords: Luminescence Nanoparticles Heterostructure PL stability Display
a b s t r a c t Perovskite quantum dots (PQDs) have excellent optical properties such as high photoluminescence quantum yield (PL QY) and high colour purity, and thus show promising application prospects in photoelectric devices. However, the poor stability of PQDs (especially red-emissive PQDs) greatly limits their applications. Herein, we synthesized CsPbBr3-xIx/ZnSe heterostructures via in-situ formation of ZnSe QDs in the red-emissive CsPbBr3-xIx PQDs, which maintains the high PL QY (70%) but greatly enhances the stability of PQDs. Subsequently, we utilized the red-emissive CsPbBr3-xIx/ZnSe heterostructures and greenemissive CsPbBr3 PQDs as the light conversion materials to fabricate a QD film, which was then applied in backlight display with ultra-wide colour gamut up to NTSC 125%. Ó 2019 Elsevier B.V. All rights reserved.
1. Introduction Quantum dots (QDs) have been considered to be promising light-emitting materials for the next generation of displays [1–4]. In particular, perovskite quantum dots (PQDs) have become a research hotspot, owing to their superior optical properties such as high photoluminescence (PL) quantum yield (QY) and high colour purity [5,6]. However, the stability of PQDs is poor, especially for red-emissive PQDs. Changes in humidity, light, and temperature may all cause the decrease of PL QY and the blue shift of emission wavelength [7,8]. This defect greatly limits the application of PQDs in optoelectronic devices. Herein, we report the moderate synthesis of red-emissive CsPbBr3-xIx/ZnSe heterostructures with significantly improved stability and their application as colour conversion materials for ultra-wide colour gamut backlight display (Fig. 1). We synthesized red-emissive CsPbBr3-xIx PQDs, followed by in-situ formation of ZnSe QDs, to obtain CsPbBr3-xIx/ZnSe heterostructures possessing high PL QY and much better PL stability that no blue-shift was observed after 7-day storage. Subsequently, we combined the green CsPbBr3 PQDs and the as prepared CsPbBr3-xIx/ZnSe heterostructures as colour conversion materials to fabricate ultra-wide colour gamut QDs film with the assistance of a
⇑ Corresponding authors. E-mail addresses: [email protected] (C.-F. Wang), [email protected]. cn (S. Chen). 1 Zhangchi Chen currently studies at Nanjing Foreign Language School, China. https://doi.org/10.1016/j.matlet.2019.07.021 0167-577X/Ó 2019 Elsevier B.V. All rights reserved.
laboratory coater. The colour gamut of the film is 125%, far exceeding the 72% colour gamut of commercial liquid crystal displays [9]. 2. Experimental section 2.1. Preparation of red-emissive CsPbBr3-xIx/ZnSe heterostructures The CsPbBr3 and CsPbBr3-xIx PQDs were synthesized according to previously reported method [10] with proper modification (See the experimental details in Supplementary Information). 0.0211 g of Se powder was added into a 5 mL vial, followed by the addition of TOP (1 mL). After stirring for 20 min, a colourless and transparent Se precursor was obtained. A toluene solution of CsPbBr3-xIx (10 mL) and 0.049 g of zinc stearate were added into a 50 mL four-necked flask, stirred under N2 atmosphere for 30 min. Then the Se precursor was injected into the above solution, and the mixture was continuously stirred for different time (10, 20, 30, 40, and 50 min, respectively) to prepare CsPbBr3-xIx/ZnSe heterostructures. 2.2. Preparation of QD film The QD film was prepared according to a method reported previously [11]. A toluene solution of green-emissive CsPbBr3 PQDs (5 mL), a toluene solution of CsPbBr3-xIx/ZnSe heterostructures (1 mL) were mixed with optical coating (10 g) in a 25 mL beaker, stirred violently for 10 min to obtain a homogeneous QD solution. Subsequently, the QD solution was coated on the expansion film
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Fig. 1. Schematic demonstrations of the synthesis of CsPbBr3-xIx/ZnSe heterostructures and their application in display.
with the assistance of laboratory coating machine for 8 times (The expansion film is a part of backlight units in liquid crystal display (LCD), and it has a rough and uniform surface to facilitate filmforming). Finally, the QD film was dried in vacuum oven for 6 h. 3. Results and discussion In this work, we prepared red-emissive CsPbBr3-xIx/ZnSe heterostructures with good stability by in-situ formation of ZnSe QDs in CsPbBr3-xIx PQDs. Transmission electron microscopy (TEM) was performed to confirm the heterostructure of CsPbBr3-xIx/ZnSe. As shown in Fig. 2a, the as-prepared nanoparticles have a good dispersity and narrow size distribution with mean size of 9.2 nm (Fig. S1). The inset in Fig. 2a shows a typical HRTEM image of CsPbBr3-xIx/ZnSe heterostructure, where a ZnSe QD with lattice spacing of 0.20 nm is captured on the surface of a CsPbBr3xIx PQD with lattice spacing of 0.58 nm. The similar feature has been previously reported in perovskite-based heterostrucrue [12], and this should be a powerful evidence to justify the formation of CsPbBr3-xIx/ZnSe heterostrucrue as claimed. Fig. 2b shows the X-ray diffraction (XRD) patterns of CsPbBr3-xIx PQDs and CsPbBr3-xIx/ZnSe heterostructures, and the XRD data for bulk ZnSe is also shown as reference (JCPDS Card No. 37-1463) [13]. It can be seen that there are 3 extra peaks in CsPbBr3-xIx/ZnSe heterostructures XRD pattern at 27.2°, 45.2° and 53.5°, corresponding to the (1 1 1), (2 2 0) and (3 1 1) plane of ZnSe, respectively. The TEM and XRD results suggest that the CsPbBr3-xIx/ZnSe heterostructures was successfully prepared. The optimal reaction time for the preparation of CsPbBr3-xIx/ZnSe heterostructures was investigated. The time for in-situ formation ZnSe QDs in the CsPbBr3-xIx solution was set as 10, 20, 30, 40 and 50 min, respectively. Optical analyses were performed immediately after the reaction. The PL peak of CsPbBr3-xIx PQDs was centered at 608 nm with full width at half maximum (FWHM) of 30 nm (Fig. 2c). Upon the incorporation of ZnSe QDs into CsPbBr3-xIx PQDs, the PL peak of the resulting CsPbBr3-xIx/ZnSe heterostructures red shifted to 625 nm, along with FWHM of 34 nm. The red-shift of the PL peak might be ascribed to the reduced quantum confinement effect of CsPbBr3-xIx/ZnSe heterostructures, resulting in shrinking of the bandgap [14]. We noted that a shoulder appeared at 575 nm in the PL spectra of
CsPbBr3-xIx/ZnSe heterostructures with the reaction time from 10 to 40 min, while the samples obtained from 40 and 50 min showed fine PL peaks. This phenomenon should be attributed to the generation of Pb-doped ZnSe QDs due to the dissociative Pb2+ in the solution at the initial stage of the reaction [15]; such dissociative Pb-doped ZnSe QDs combined with the CsPbBr3-xIx PQDs upon prolonged reaction time, resulting in the disappearance of the shoulder. The PL QYs of CsPbBr3-xIx/ZnSe heterostructures obtained from different reaction times were all determined to be ca. 70% (Fig. S2), indicating that the doping of ZnSe QDs didn’t destroy the structure of CsPbBr3-xIx PQDs. In the stability experiment, we selected the CsPbBr3-xIx PQDs and the CsPbBr3-xIx/ZnSe heterostructures obtained from 50 min stirring time for comparison. The PL intensity of CsPbBr3-xIx PQDs decreases with time, accompanied by a significant blue shift phenomenon (Fig. 2d). After 2 days, the emission peak shifts from 608 to 520 nm, along with 70% drop in PL intensity. This feature reveals the poor stability of CsPbBr3-xIx PQDs. However, for CsPbBr3-xIx/ZnSe heterostructures exposed in atmosphere for 7 days, there is no significant blue-shift phenomenon, and the PL intensity is only reduced by about 33% (Fig. 2e). The stability of CsPbBr3-xIx/ZnSe heterostructures under UV-light was also tested. The PL quenching and blue-shift slightly speeded up simultaneously (Fig. 2f). Apparently, compared to CsPbBr3-xIx PQDs, the stability of CsPbBr3-xIx/ZnSe heterostructures has been raised to a higher level. We further explored the application of CsPbBr3-xIx/ZnSe heterostructures as colour-converting film for backlight display. Fig. 3a shows a simplified model of the backlight display mainly consisting of three parts: a liquid crystal panel, a QD film, and a blue backlight. Green-emissive CsPbBr3 PQDs (Fig. S3), CsPbBr3-xIx/ZnSe heterostructures and optical coating mixture were coated on the expansion film to yield the QD film. Fig. 3b and c are digital photographs of a finished QD film taken under sunlight and UV light, respectively. The PQDs are uniformly dispersed in the coating to exhibit satisfactory PL property. The optical quality of the simplified QD-based backlight display was investigated. Fig. 3d shows the emission spectra of the simplified QD-based backlight display. It can be seen that the emission wavelengths of red and green are 622 and 525 nm, and the corresponding FWHMs are 33 and 18 nm, respectively. The colour gamut of
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Fig. 2. (a) TEM image of CsPbBr3-xIx/ZnSe heterostructures. Inset: HRTEM image of the corresponding QDs (scale bar: 5 nm). (b) XRD patterns of CsPbBr3-xIx PQDs and CsPbBr3-xIx/ZnSe heterostructures. (c) PL spectra of CsPbBr3-xIx/ZnSe heterostructures obtained from different reaction times. (d) Stability analyses of CsPbBr3-xIx PQDs. (e, f) Stability of CsPbBr3-xIx/ZnSe heterostructures (e) under natural light in atmosphere and (f) under 365 nm UV-light.
Fig. 3. (a) A simplified model of the backlight display. (b, c) Digital photographs of the QD film taken (b) under daylight and (c) UV light. (d) Emission spectra of the display device. (e) Colour gamut of the display device (black solid line) compared to NTSC 1931 (dashed line). (f) Performance of a backlight display with the QD film covering only half the display (right side).
the QD-based backlight display prepared in the work is 125% compared to that of NTSC 1931 (Fig. 3e). We also applied the as prepared QD film in a semi-finished backlight display to verify the feasibility. The performance of the display device with QD film covering only half the display is shown in Fig. 3f, indicating the QDbased backlight display has satisfactory display performance.
4. Conclusion We demonstrated the moderate synthesis of red-emissive CsPbBr3-xIx/ZnSe heterostructures with significantly improved PL stability and their application as colour conversion materials for ultra-wide colour gamut display. The in-situ formation of ZnSe
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QDs in CsPbBr3-xIx PQD solution yielded CsPbBr3-xIx/ZnSe heterostructures with high PL quantum yield and significantly improved PL stability. We also investigated the use of the heterostructures as colour conversion materials for display backlight, to achieve colour gamut up to 125%. This work presents a facile route enabling the realization of perovskite QDs potential for high-colour-quality light-emitting applications.
Declaration of Competing Interest The authors declare that they have no competing financial interests.
Acknowledgements This work was supported by National Natural Science Foundation of China (21736006) and Jiangsu Students’ Innovation and Entrepreneurship Training Program (2018DC330).
Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.matlet.2019.07.021.
References [1] H.C. Yoon, H. Lee, H. Kang, J.H. Oh, Y.R. Do, J. Mater. Chem. C 6 (2018) 13023– 13033. [2] K. Ma, X.-Y. Du, Y.-W. Zhang, S. Chen, J. Mater. Chem. C 5 (2017) 9398–9404. [3] X. Dai, Z. Zhang, Y. Jin, Y. Niu, H. Cao, X. Liang, L. Chen, J. Wang, X. Peng, Nature 515 (2014) 96–99. [4] L. He, M. Fei, J. Chen, Y. Tian, Y. Jiang, Y. Huang, K. Xu, J. Hu, Z. Zhao, Q. Zhang, H. Ni, L. Chen, Mater. Today 22 (2019) 76–84. [5] J. Song, J. Li, X. Li, L. Xu, Y. Dong, H. Zeng, Adv. Mater. 27 (2015) 7162–7167. [6] C. Fan, X. Xu, K. Yang, F. Jiang, S. Wang, Q. Zhang, Adv. Mater. 30 (2018) 1804707. [7] B.A. Koscher, N.D. Bronstein, J.H. Olshansky, Y. Bekenstein, A.P. Alivisatos, J. Am. Chem. Soc. 138 (2016) 12065–12068. [8] A. Loiudice, S. Saris, E. Oveisi, D.T.L. Alexander, R. Buonsanti, Angew. Chem. Int. Ed. 56 (2017) 10696–10701. [9] H.-C. Wang, S.-Y. Lin, A.-C. Tang, B.P. Singh, H. Tong, C.-Y. Chen, Y.-C. Lee, T.-L. Tsai, R.-S. Liu, Angew. Chem. Int. Ed. 55 (2016) 7924–7929. [10] L. Protesescu, S. Yakunin, M.I. Bodnarchuk, F. Krieg, R. Caputo, C.H. Hendon, R. X. Yang, A. Walsh, M.V. Kovalenko, Nano Lett. 15 (2015) 3692–3696. [11] R. Cheng, F. Li, J. Zhang, X. She, Y. Zhang, K. Shao, Y. Lin, C.-F. Wang, S. Chen, J. Mater. Chem. C 7 (2019) 4244–4249. [12] W. Chen, J. Hao, W. Hu, Z. Zang, X. Tang, L. Fang, T. Niu, M. Zhou, Small 13 (2017) 1604085. [13] B. Hou, Y. Li, Y. Liu, B. Yuan, M. Jia, F. Jiang, CrystEngComm 11 (2009) 1789– 1792. [14] Z. Ning, X. Gong, R. Comin, G. Walters, F. Fan, O. Voznyy, E. Yassitepe, A. Buin, S. Hoogland, E.H. Sargent, Nature 523 (2015) 324–328. [15] Y. Mita, R. Kuronuma, M. Inoue, S. Sasaki, Y. Miyamoto, J. Appl. Phys. 96 (2004) 1904–1908.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
Preparation of heterostructure quantum dots towards wide-colour-gamut display Rui Cheng, Haixia Shen, Zhangchi Chen 1, Fucheng Li, Ge Li, Cai-Feng Wang ⇑, Su Chen ⇑ State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing 210009, China
a r t i c l e
i n f o
Article history: Received 11 April 2019 Received in revised form 26 June 2019 Accepted 7 July 2019 Available online 8 July 2019 Keywords: Luminescence Nanoparticles Heterostructure PL stability Display
a b s t r a c t Perovskite quantum dots (PQDs) have excellent optical properties such as high photoluminescence quantum yield (PL QY) and high colour purity, and thus show promising application prospects in photoelectric devices. However, the poor stability of PQDs (especially red-emissive PQDs) greatly limits their applications. Herein, we synthesized CsPbBr3-xIx/ZnSe heterostructures via in-situ formation of ZnSe QDs in the red-emissive CsPbBr3-xIx PQDs, which maintains the high PL QY (70%) but greatly enhances the stability of PQDs. Subsequently, we utilized the red-emissive CsPbBr3-xIx/ZnSe heterostructures and greenemissive CsPbBr3 PQDs as the light conversion materials to fabricate a QD film, which was then applied in backlight display with ultra-wide colour gamut up to NTSC 125%. Ó 2019 Elsevier B.V. All rights reserved.
1. Introduction Quantum dots (QDs) have been considered to be promising light-emitting materials for the next generation of displays [1–4]. In particular, perovskite quantum dots (PQDs) have become a research hotspot, owing to their superior optical properties such as high photoluminescence (PL) quantum yield (QY) and high colour purity [5,6]. However, the stability of PQDs is poor, especially for red-emissive PQDs. Changes in humidity, light, and temperature may all cause the decrease of PL QY and the blue shift of emission wavelength [7,8]. This defect greatly limits the application of PQDs in optoelectronic devices. Herein, we report the moderate synthesis of red-emissive CsPbBr3-xIx/ZnSe heterostructures with significantly improved stability and their application as colour conversion materials for ultra-wide colour gamut backlight display (Fig. 1). We synthesized red-emissive CsPbBr3-xIx PQDs, followed by in-situ formation of ZnSe QDs, to obtain CsPbBr3-xIx/ZnSe heterostructures possessing high PL QY and much better PL stability that no blue-shift was observed after 7-day storage. Subsequently, we combined the green CsPbBr3 PQDs and the as prepared CsPbBr3-xIx/ZnSe heterostructures as colour conversion materials to fabricate ultra-wide colour gamut QDs film with the assistance of a
⇑ Corresponding authors. E-mail addresses: [email protected] (C.-F. Wang), [email protected]. cn (S. Chen). 1 Zhangchi Chen currently studies at Nanjing Foreign Language School, China. https://doi.org/10.1016/j.matlet.2019.07.021 0167-577X/Ó 2019 Elsevier B.V. All rights reserved.
laboratory coater. The colour gamut of the film is 125%, far exceeding the 72% colour gamut of commercial liquid crystal displays [9]. 2. Experimental section 2.1. Preparation of red-emissive CsPbBr3-xIx/ZnSe heterostructures The CsPbBr3 and CsPbBr3-xIx PQDs were synthesized according to previously reported method [10] with proper modification (See the experimental details in Supplementary Information). 0.0211 g of Se powder was added into a 5 mL vial, followed by the addition of TOP (1 mL). After stirring for 20 min, a colourless and transparent Se precursor was obtained. A toluene solution of CsPbBr3-xIx (10 mL) and 0.049 g of zinc stearate were added into a 50 mL four-necked flask, stirred under N2 atmosphere for 30 min. Then the Se precursor was injected into the above solution, and the mixture was continuously stirred for different time (10, 20, 30, 40, and 50 min, respectively) to prepare CsPbBr3-xIx/ZnSe heterostructures. 2.2. Preparation of QD film The QD film was prepared according to a method reported previously [11]. A toluene solution of green-emissive CsPbBr3 PQDs (5 mL), a toluene solution of CsPbBr3-xIx/ZnSe heterostructures (1 mL) were mixed with optical coating (10 g) in a 25 mL beaker, stirred violently for 10 min to obtain a homogeneous QD solution. Subsequently, the QD solution was coated on the expansion film
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Fig. 1. Schematic demonstrations of the synthesis of CsPbBr3-xIx/ZnSe heterostructures and their application in display.
with the assistance of laboratory coating machine for 8 times (The expansion film is a part of backlight units in liquid crystal display (LCD), and it has a rough and uniform surface to facilitate filmforming). Finally, the QD film was dried in vacuum oven for 6 h. 3. Results and discussion In this work, we prepared red-emissive CsPbBr3-xIx/ZnSe heterostructures with good stability by in-situ formation of ZnSe QDs in CsPbBr3-xIx PQDs. Transmission electron microscopy (TEM) was performed to confirm the heterostructure of CsPbBr3-xIx/ZnSe. As shown in Fig. 2a, the as-prepared nanoparticles have a good dispersity and narrow size distribution with mean size of 9.2 nm (Fig. S1). The inset in Fig. 2a shows a typical HRTEM image of CsPbBr3-xIx/ZnSe heterostructure, where a ZnSe QD with lattice spacing of 0.20 nm is captured on the surface of a CsPbBr3xIx PQD with lattice spacing of 0.58 nm. The similar feature has been previously reported in perovskite-based heterostrucrue [12], and this should be a powerful evidence to justify the formation of CsPbBr3-xIx/ZnSe heterostrucrue as claimed. Fig. 2b shows the X-ray diffraction (XRD) patterns of CsPbBr3-xIx PQDs and CsPbBr3-xIx/ZnSe heterostructures, and the XRD data for bulk ZnSe is also shown as reference (JCPDS Card No. 37-1463) [13]. It can be seen that there are 3 extra peaks in CsPbBr3-xIx/ZnSe heterostructures XRD pattern at 27.2°, 45.2° and 53.5°, corresponding to the (1 1 1), (2 2 0) and (3 1 1) plane of ZnSe, respectively. The TEM and XRD results suggest that the CsPbBr3-xIx/ZnSe heterostructures was successfully prepared. The optimal reaction time for the preparation of CsPbBr3-xIx/ZnSe heterostructures was investigated. The time for in-situ formation ZnSe QDs in the CsPbBr3-xIx solution was set as 10, 20, 30, 40 and 50 min, respectively. Optical analyses were performed immediately after the reaction. The PL peak of CsPbBr3-xIx PQDs was centered at 608 nm with full width at half maximum (FWHM) of 30 nm (Fig. 2c). Upon the incorporation of ZnSe QDs into CsPbBr3-xIx PQDs, the PL peak of the resulting CsPbBr3-xIx/ZnSe heterostructures red shifted to 625 nm, along with FWHM of 34 nm. The red-shift of the PL peak might be ascribed to the reduced quantum confinement effect of CsPbBr3-xIx/ZnSe heterostructures, resulting in shrinking of the bandgap [14]. We noted that a shoulder appeared at 575 nm in the PL spectra of
CsPbBr3-xIx/ZnSe heterostructures with the reaction time from 10 to 40 min, while the samples obtained from 40 and 50 min showed fine PL peaks. This phenomenon should be attributed to the generation of Pb-doped ZnSe QDs due to the dissociative Pb2+ in the solution at the initial stage of the reaction [15]; such dissociative Pb-doped ZnSe QDs combined with the CsPbBr3-xIx PQDs upon prolonged reaction time, resulting in the disappearance of the shoulder. The PL QYs of CsPbBr3-xIx/ZnSe heterostructures obtained from different reaction times were all determined to be ca. 70% (Fig. S2), indicating that the doping of ZnSe QDs didn’t destroy the structure of CsPbBr3-xIx PQDs. In the stability experiment, we selected the CsPbBr3-xIx PQDs and the CsPbBr3-xIx/ZnSe heterostructures obtained from 50 min stirring time for comparison. The PL intensity of CsPbBr3-xIx PQDs decreases with time, accompanied by a significant blue shift phenomenon (Fig. 2d). After 2 days, the emission peak shifts from 608 to 520 nm, along with 70% drop in PL intensity. This feature reveals the poor stability of CsPbBr3-xIx PQDs. However, for CsPbBr3-xIx/ZnSe heterostructures exposed in atmosphere for 7 days, there is no significant blue-shift phenomenon, and the PL intensity is only reduced by about 33% (Fig. 2e). The stability of CsPbBr3-xIx/ZnSe heterostructures under UV-light was also tested. The PL quenching and blue-shift slightly speeded up simultaneously (Fig. 2f). Apparently, compared to CsPbBr3-xIx PQDs, the stability of CsPbBr3-xIx/ZnSe heterostructures has been raised to a higher level. We further explored the application of CsPbBr3-xIx/ZnSe heterostructures as colour-converting film for backlight display. Fig. 3a shows a simplified model of the backlight display mainly consisting of three parts: a liquid crystal panel, a QD film, and a blue backlight. Green-emissive CsPbBr3 PQDs (Fig. S3), CsPbBr3-xIx/ZnSe heterostructures and optical coating mixture were coated on the expansion film to yield the QD film. Fig. 3b and c are digital photographs of a finished QD film taken under sunlight and UV light, respectively. The PQDs are uniformly dispersed in the coating to exhibit satisfactory PL property. The optical quality of the simplified QD-based backlight display was investigated. Fig. 3d shows the emission spectra of the simplified QD-based backlight display. It can be seen that the emission wavelengths of red and green are 622 and 525 nm, and the corresponding FWHMs are 33 and 18 nm, respectively. The colour gamut of
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Fig. 2. (a) TEM image of CsPbBr3-xIx/ZnSe heterostructures. Inset: HRTEM image of the corresponding QDs (scale bar: 5 nm). (b) XRD patterns of CsPbBr3-xIx PQDs and CsPbBr3-xIx/ZnSe heterostructures. (c) PL spectra of CsPbBr3-xIx/ZnSe heterostructures obtained from different reaction times. (d) Stability analyses of CsPbBr3-xIx PQDs. (e, f) Stability of CsPbBr3-xIx/ZnSe heterostructures (e) under natural light in atmosphere and (f) under 365 nm UV-light.
Fig. 3. (a) A simplified model of the backlight display. (b, c) Digital photographs of the QD film taken (b) under daylight and (c) UV light. (d) Emission spectra of the display device. (e) Colour gamut of the display device (black solid line) compared to NTSC 1931 (dashed line). (f) Performance of a backlight display with the QD film covering only half the display (right side).
the QD-based backlight display prepared in the work is 125% compared to that of NTSC 1931 (Fig. 3e). We also applied the as prepared QD film in a semi-finished backlight display to verify the feasibility. The performance of the display device with QD film covering only half the display is shown in Fig. 3f, indicating the QDbased backlight display has satisfactory display performance.
4. Conclusion We demonstrated the moderate synthesis of red-emissive CsPbBr3-xIx/ZnSe heterostructures with significantly improved PL stability and their application as colour conversion materials for ultra-wide colour gamut display. The in-situ formation of ZnSe
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QDs in CsPbBr3-xIx PQD solution yielded CsPbBr3-xIx/ZnSe heterostructures with high PL quantum yield and significantly improved PL stability. We also investigated the use of the heterostructures as colour conversion materials for display backlight, to achieve colour gamut up to 125%. This work presents a facile route enabling the realization of perovskite QDs potential for high-colour-quality light-emitting applications.
Declaration of Competing Interest The authors declare that they have no competing financial interests.
Acknowledgements This work was supported by National Natural Science Foundation of China (21736006) and Jiangsu Students’ Innovation and Entrepreneurship Training Program (2018DC330).
Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.matlet.2019.07.021.
References [1] H.C. Yoon, H. Lee, H. Kang, J.H. Oh, Y.R. Do, J. Mater. Chem. C 6 (2018) 13023– 13033. [2] K. Ma, X.-Y. Du, Y.-W. Zhang, S. Chen, J. Mater. Chem. C 5 (2017) 9398–9404. [3] X. Dai, Z. Zhang, Y. Jin, Y. Niu, H. Cao, X. Liang, L. Chen, J. Wang, X. Peng, Nature 515 (2014) 96–99. [4] L. He, M. Fei, J. Chen, Y. Tian, Y. Jiang, Y. Huang, K. Xu, J. Hu, Z. Zhao, Q. Zhang, H. Ni, L. Chen, Mater. Today 22 (2019) 76–84. [5] J. Song, J. Li, X. Li, L. Xu, Y. Dong, H. Zeng, Adv. Mater. 27 (2015) 7162–7167. [6] C. Fan, X. Xu, K. Yang, F. Jiang, S. Wang, Q. Zhang, Adv. Mater. 30 (2018) 1804707. [7] B.A. Koscher, N.D. Bronstein, J.H. Olshansky, Y. Bekenstein, A.P. Alivisatos, J. Am. Chem. Soc. 138 (2016) 12065–12068. [8] A. Loiudice, S. Saris, E. Oveisi, D.T.L. Alexander, R. Buonsanti, Angew. Chem. Int. Ed. 56 (2017) 10696–10701. [9] H.-C. Wang, S.-Y. Lin, A.-C. Tang, B.P. Singh, H. Tong, C.-Y. Chen, Y.-C. Lee, T.-L. Tsai, R.-S. Liu, Angew. Chem. Int. Ed. 55 (2016) 7924–7929. [10] L. Protesescu, S. Yakunin, M.I. Bodnarchuk, F. Krieg, R. Caputo, C.H. Hendon, R. X. Yang, A. Walsh, M.V. Kovalenko, Nano Lett. 15 (2015) 3692–3696. [11] R. Cheng, F. Li, J. Zhang, X. She, Y. Zhang, K. Shao, Y. Lin, C.-F. Wang, S. Chen, J. Mater. Chem. C 7 (2019) 4244–4249. [12] W. Chen, J. Hao, W. Hu, Z. Zang, X. Tang, L. Fang, T. Niu, M. Zhou, Small 13 (2017) 1604085. [13] B. Hou, Y. Li, Y. Liu, B. Yuan, M. Jia, F. Jiang, CrystEngComm 11 (2009) 1789– 1792. [14] Z. Ning, X. Gong, R. Comin, G. Walters, F. Fan, O. Voznyy, E. Yassitepe, A. Buin, S. Hoogland, E.H. Sargent, Nature 523 (2015) 324–328. [15] Y. Mita, R. Kuronuma, M. Inoue, S. Sasaki, Y. Miyamoto, J. Appl. Phys. 96 (2004) 1904–1908.