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1. Extending the Defect Tolerance of Halide Perovskite Nanocrystals to Hot Carrier Cooling Dynamics

Author

Ye, Junzhi, Mondal, Navendu, Carwithen, Ben P., Zhang, Yunwei, Dai, Linjie, Fan, Xiangbin, Mao, Jian, Cui, Zhiqiang, Ghosh, Pratyush, Martinez, Clara Otero, van Turnhout, Lars, Yu, Zhongzheng, Chen, Ziming, Greenham, Neil C., Stranks, Samuel D., Polavarapu, Lakshminarayana, Bakulin, Artem, Rao, Akshay, and Hoye, Robert L. Z.

Subjects
Physics - Applied Physics
Abstract

Defect tolerance is a critical enabling factor for efficient lead-halide perovskite materials, but the current understanding is primarily on band-edge (cold) carriers, with significant debate over whether hot carriers (HCs) can also exhibit defect tolerance. Here, this important gap in the field is addressed by investigating how internationally-introduced traps affect HC relaxation in CsPbX3 nanocrystals (X = Br, I, or mixture). Using femtosecond interband and intraband spectroscopy, along with energy-dependent photoluminescence measurements and kinetic modelling, it is found that HCs are not universally defect tolerant in CsPbX3, but are strongly correlated to the defect tolerance of cold carriers, requiring shallow traps to be present (as in CsPbI3). It is found that HCs are directly captured by traps, instead of going through an intermediate cold carrier, and deeper traps cause faster HC cooling, reducing the effects of the hot phonon bottleneck and Auger reheating. This work provides important insights into how defects influence HCs, which will be important for designing materials for hot carrier solar cells, multiexciton generation, and optical gain media., Comment: 18 pages, 5 figures

Published
2024

3. Direct linearly polarized electroluminescence from perovskite nanoplatelet superlattices

Author

Ye, Junzhi, Ren, Aobo, Dai, Linjie, Baikie, Tomi K., Guo, Renjun, Pal, Debapriya, Gorgon, Sebastian, Heger, Julian E., Huang, Junyang, Sun, Yuqi, Arul, Rakesh, Grimaldi, Gianluca, Zhang, Kaiwen, Shamsi, Javad, Huang, Yi-Teng, Wang, Hao, Wu, Jiang, Koenderink, A. Femius, Torrente Murciano, Laura, Schwartzkopf, Matthias, Roth, Stephen V., Müller-Buschbaum, Peter, Baumberg, Jeremy J., Stranks, Samuel D., Greenham, Neil C., Polavarapu, Lakshminarayana, Zhang, Wei, Rao, Akshay, and Hoye, Robert L. Z.

Published
2024
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4. Efficient blue electroluminescence from reduced-dimensional perovskites

Author

Yuan, Shuai, Dai, Linjie, Sun, Yuqi, Auras, Florian, Zhou, Yu-Hang, An, Rui-Zhi, Liu, Yun, Ding, Chenfeng, Cassidy, Cathal, Tang, Xun, Dong, Shou-Cheng, Kang, Hyung-Been, Chen, Kai, Liu, Xiaomin, Ye, Zhi-Feng, Zhao, Yixin, Adachi, Chihaya, Liao, Liang-Sheng, Greenham, Neil C., Qi, Yabing, Stranks, Samuel D., Cui, Lin-Song, and Friend, Richard H.

Published
2024
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5. High carrier mobility along the [111] orientation in Cu2O photoelectrodes

Author

Pan, Linfeng, Dai, Linjie, Burton, Oliver J., Chen, Lu, Andrei, Virgil, Zhang, Youcheng, Ren, Dan, Cheng, Jinshui, Wu, Linxiao, Frohna, Kyle, Abfalterer, Anna, Yang, Terry Chien-Jen, Niu, Wenzhe, Xia, Meng, Hofmann, Stephan, Dyson, Paul J., Reisner, Erwin, Sirringhaus, Henning, Luo, Jingshan, Hagfeldt, Anders, Grätzel, Michael, and Stranks, Samuel D.

Published
2024
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6. Fast near-infrared photodetectors based on nontoxic and solution-processable AgBiS2

Author

Huang, Yi-Teng, Nodari, Davide, Furlan, Francesco, Zhang, Youcheng, Rusu, Marin, Dai, Linjie, Andaji-Garmaroudi, Zahra, Stranks, Samuel D., Sirringhaus, Henning, Rao, Akshay, Gasparini, Nicola, and Hoye, Robert L. Z.

Subjects
Condensed Matter - Materials Science
Abstract

Solution-processable near-infrared (NIR) photodetectors are urgently needed for a wide range of next-generation electronics, including sensors, optical communications and bioimaging. However, there is currently a compromise between low toxicity and slow (<300 kHz cut-off frequency) organic materials versus faster detectors (>300 kHz cut-off frequency) based on compounds containing toxic lead or cadmium. Herein, we circumvent this trade-off by developing solution-processed AgBiS2 photodetectors with high cut-off frequencies under both white light (>1 MHz) and NIR (approaching 500 kHz) illumination. These high cut-off frequencies are due to the short transit distances of charge-carriers in the AgBiS2 photodetectors, which arise from the strong light absorption of these materials, such that film thicknesses well below 120 nm are adequate to absorb >65% of near-infrared to visible light. By finely controlling the thickness of the photoactive layer, we can modulate the charge-collection efficiency, achieve low dark current densities, and minimize the effects of ion migration to realize fast photodetectors that are stable in air. These outstanding characteristics enable real-time heartbeat sensors based on NIR AgBiS2 photodetectors. # equal contribution, * corresponding authors, Comment: 29 pages, 4 figures, 1 table

Published
2023
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7. Tailoring Interlayer Charge Transfer Dynamics in 2D Perovskites with Electroactive Spacer Molecules

Author

Boeije, Yorrick, Van Gompel, Wouter T. M., Zhang, Youcheng, Ghosh, Pratyush, Zelewski, Szymon J., Maufort, Arthur, Roose, Bart, Ooi, Zher Ying, Chowdhury, Rituparno, Devroey, Ilan, Lenaers, Stijn, Tew, Alasdair, Dai, Linjie, Dey, Krishanu, Salway, Hayden, Friend, Richard H., Sirringhaus, Henning, Lutsen, Laurence, Vanderzande, Dirk, Rao, Akshay, and Stranks, Samuel D.

Subjects
Physics - Applied Physics, Condensed Matter - Materials Science
Abstract

The family of hybrid organic-inorganic lead-halide perovskites are the subject of intense interest for optoelectronic applications, from light-emitting diodes to photovoltaics to X-ray detectors. Due to the inert nature of most organic molecules, the inorganic sublattice generally dominates the electronic structure and therefore optoelectronic properties of perovskites. Here, we use optically and electronically active carbazole-based Cz-Ci molecules, where Ci indicates an alkylammonium chain and i indicates the number of CH2 units in the chain, varying from 3-5, as cations in the 2D perovskite structure. By investigating the photophysics and charge transport characteristics of (Cz-Ci)2PbI4, we demonstrate a tunable electronic coupling between the inorganic lead-halide and organic layers. The strongest interlayer electronic coupling was found for (Cz-C3)2PbI4, where photothermal deflection spectroscopy results remarkably demonstrate an organic-inorganic charge transfer state. Ultrafast transient absorption spectroscopy measurements demonstrate ultrafast hole transfer from the photoexcited lead-halide layer to the Cz-Ci molecules, the efficiency of which increases by varying the chain length from i=5 to i=3. The charge transfer results in long-lived carriers (10-100 ns) and quenched emission, in stark contrast with the fast (sub-ns) and efficient radiative decay of bound excitons in the more conventional 2D perovskite (PEA)2PbI4, in which phenylethylammonium (PEA) acts as an inert spacer. Electrical charge transport measurements further support enhanced interlayer coupling, showing increased out-of-plane carrier mobility from i=5 to i=3. This study paves the way for the rational design of 2D perovskites with combined inorganic-organic electronic proper-ties through the wide range of functionalities available in the world of organics., Comment: 16 main text pages + 20 supplemental text pages, 5 main text figures + 19 supplemental figures

Published
2023

8. Direct Linearly-Polarised Electroluminescence from Perovskite Nanoplatelet Superlattices

Author

Ye, Junzhi, Ren, Aobo, Dai, Linjie, Baikie, Tomi, Guo, Renjun, Pal, Debapriya, Gorgon, Sebastian, Heger, Julian E., Huang, Junyang, Sun, Yuqi, Arul, Rakesh, Grimaldi, Gianluca, Zhang, Kaiwen, Shamsi, Javad, Huang, Yi-Teng, Wang, Hao, Wu, Jiang, Koenderink, A. Femius, Murciano, Laura Torrente, Schwartzkopf, Matthias, Roth, Stephen V., Muller-Buschbaum, Peter, Baumberg, Jeremy J., Stranks, Samuel D., Greenham, Neil C., Polavarapu, Lakshminarayana, Zhang, Wei, Rao, Akshay, and Hoye, Robert L. Z.

Subjects
Physics - Optics, Condensed Matter - Materials Science
Abstract

Polarised light is critical for a wide range of applications, but is usually generated by filtering unpolarised light, which leads to significant energy losses and requires additional optics. Herein, the direct emission of linearly-polarised light is achieved from light-emitting diodes (LEDs) made of CsPbI3 perovskite nanoplatelet superlattices. Through use of solvents with different vapour pressures, the self-assembly of perovskite nanoplatelets is achieved to enable fine control over the orientation (either face-up or edge-up) and therefore the transition dipole moment. As a result of the highly-uniform alignment of the nanoplatelets, as well as their strong quantum and dielectric confinement, large exciton fine-structure splitting is achieved at the film level, leading to pure-red LEDs exhibiting a high degree of linear polarisation of 74.4% without any photonic structures. This work unveils the possibilities of perovskite nanoplatelets as a highly promising source of linearly-polarised electroluminescence, opening up the development of next-generation 3D displays and optical communications from this highly versatile, solution-processable system., Comment: 26 pages, 5 figures

Published
2023
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11. Publisher Correction: High carrier mobility along the [111] orientation in Cu2O photoelectrodes

Author

Pan, Linfeng, Dai, Linjie, Burton, Oliver J., Chen, Lu, Andrei, Virgil, Zhang, Youcheng, Ren, Dan, Cheng, Jinshui, Wu, Linxiao, Frohna, Kyle, Abfalterer, Anna, Yang, Terry Chien-Jen, Niu, Wenzhe, Xia, Meng, Hofmann, Stephan, Dyson, Paul J., Reisner, Erwin, Sirringhaus, Henning, Luo, Jingshan, Hagfeldt, Anders, Grätzel, Michael, and Stranks, Samuel D.

Published
2024
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12. High-bandwidth perovskite photonic sources on silicon

Author

Ren, Aobo, Wang, Hao, Dai, Linjie, Xia, Junfei, Bai, Xinyu, Butler-Caddle, Edward, Smith, Joel A., Lai, Huagui, Ye, Junzhi, Li, Xiang, Zhan, Shijie, Yao, Chunhui, Li, Zewei, Tang, Mingchu, Liu, Xueping, Bi, Jinxin, Li, Bowei, Kai, Shen, Chen, Rui, Yan, Han, Hong, Jintao, Yuan, Liming, Marko, Igor P., Wonfor, Adrian, Fu, Fan, Hindmarsh, Steven A., Sanchez, Ana M., Lloyd-Hughes, James, Sweeney, Stephen J., Rao, Akshay, Greenham, Neil C., Wu, Jiang, Li, Yanrong, Cheng, Qixiang, Friend, Richard H., Penty, Richard V., White, Ian H., Snaith, Henry J., and Zhang, Wei

Published
2023
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15. Bright and stable perovskite light-emitting diodes in the near-infrared range

Author

Sun, Yuqi, Ge, Lishuang, Dai, Linjie, Cho, Changsoon, Ferrer Orri, Jordi, Ji, Kangyu, Zelewski, Szymon J., Liu, Yun, Mirabelli, Alessandro J., Zhang, Youcheng, Huang, Jun-Yu, Wang, Yusong, Gong, Ke, Lai, May Ching, Zhang, Lu, Yang, Dan, Lin, Jiudong, Tennyson, Elizabeth M., Ducati, Caterina, Stranks, Samuel D., Cui, Lin-Song, and Greenham, Neil C.

Published
2023
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16. Carrier dynamics in perovskite nanocrystals

Author

Dai, Linjie and Greenham, Neil C.

Subjects
621.31, Photophysics, Perovskite, Nanocrystals
Abstract

In this thesis, we describe our work discovering perovskite nanocrystals with desirable optoelectronic properties for high-efficiency solar cells. Ultrafast carrier-phonon interactions in semiconductors represent a major loss of the excess energy of photoexcitations above the bandgap. We demonstrate approaches to suppress the relaxation process, which may allow the full photon energy to be usefully extracted before carrier relaxation takes place. Two distinct strategies are presented to achieve this: a hot phonon bottleneck effect and a phonon bottleneck effect. First of all, we demonstrate the synthesis of lead-based perovskite nanocrystals, tin-based perovskite nanocrystals, and tin-lead alloy perovskite nanocrystals where the electronic structure and optical properties can be tuned by composition engineering. The replacement of the toxic lead with tin may also provide a less negative impact on the environment and human health in applications. Having synthesised perovskite nanocrystals, we focus on understanding the electronic structure of nanocrystal quantum dots and the interactions between excitons, carriers and phonons. By using femtosecond spectroscopic methods, we follow the dynamics of photoexcitations inside perovskite nanocrystals. A hot phonon bottleneck effect that leads to suppressed cooling at high carrier densities is observed in both hybrid and inorganic tin-lead alloy nanocrystals. Tin addition is confirmed to prolong the carrier cooling time in nanocrystal alloys, which we attribute to suppressed Klemens decay. Since a hot phonon bottleneck only takes place at extremely high fluence which is not achievable under one sun illumination, we further explore a slow relaxation occurring at low carrier densities in tin-based perovskite nanocrystals, making it practically relevant. We attribute the slow relaxation to a phonon bottleneck effect where a decreased density of states due to quantum confinement is realised between the high-energy and the low-energy states. Photodegradation measurements reveal that the high-energy signal in transient absorption spectroscopy results from two spectrally-overlapping energy levels, both of which may contribute to the slow cooling. This makes the process complicated but more attractive. The slow relaxation we observe offers new insights into the intrinsic photophysics of perovskite nanocrystals, with direct implications for photovoltaic applications where suppressed relaxation could lead to high-efficiency solar cells.

Published
2021
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18. Heterostructures enhance the absorption of lanthanides

Author

Tew, Alasdair, primary, van Turnhout, Lars, additional, Deng, Yunzhou, additional, Arul, Rakesh, additional, Ye, Junzhi, additional, Liu, Tianjun, additional, Jiang, Zhao, additional, Dai, Linjie, additional, Zhu, Huangtianzhi, additional, Zhang, Yan, additional, Rao, Akshay, additional, and Yu, Zhongzheng, additional

Published
2024
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19. High-efficiency perovskite-polymer bulk heterostructure light-emitting diodes

Author

Zhao, Baodan, Bai, Sai, Kim, Vincent, Lamboll, Robin, Shivanna, Ravichandran, Auras, Florian, Richter, Johannes M., Yang, Le, Dai, Linjie, Alsari, Mejd, She, Xiao-Jian, Liang, Lusheng, Zhang, Jiangbin, Lilliu, Samuele, Gao, Peng, Snaith, Henry J., Wang, Jianpu, Greenham, Neil C., Friend, Richard H., and Di, Dawei

Subjects
Physics - Applied Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science, Physics - Optics
Abstract

Perovskite-based optoelectronic devices have gained significant attention due to their remarkable performance and low processing cost, particularly for solar cells. However, for perovskite light-emitting diodes (LEDs), non-radiative charge carrier recombination has limited electroluminescence (EL) efficiency. Here we demonstrate perovskite-polymer bulk heterostructure LEDs exhibiting record-high external quantum efficiencies (EQEs) exceeding 20%, and an EL half-life of 46 hours under continuous operation. This performance is achieved with an emissive layer comprising quasi-2D and 3D perovskites and an insulating polymer. Transient optical spectroscopy reveals that photogenerated excitations at the quasi-2D perovskite component migrate to lower-energy sites within 1 ps. The dominant component of the photoluminescence (PL) is primarily bimolecular and is characteristic of the 3D regions. From PL quantum efficiency and transient kinetics of the emissive layer with/without charge-transport contacts, we find non-radiative recombination pathways to be effectively eliminated. Light outcoupling from planar LEDs, as used in OLED displays, generally limits EQE to 20-30%, and we model our reported EL efficiency of over 20% in the forward direction to indicate the internal quantum efficiency (IQE) to be close to 100%. Together with the low drive voltages needed to achieve useful photon fluxes (2-3 V for 0.1-1 mA/cm2), these results establish that perovskite-based LEDs have significant potential for light-emission applications.

Published
2018
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20. Strong absorption and ultrafast localisation in NaBiS2 nanocrystals with slow charge-carrier recombination

Author

Huang, Yi-Teng, Kavanagh, Seán R., Righetto, Marcello, Rusu, Marin, Levine, Igal, Unold, Thomas, Zelewski, Szymon J., Sneyd, Alexander J., Zhang, Kaiwen, Dai, Linjie, Britton, Andrew J., Ye, Junzhi, Julin, Jaakko, Napari, Mari, Zhang, Zhilong, Xiao, James, Laitinen, Mikko, Torrente-Murciano, Laura, Stranks, Samuel D., Rao, Akshay, Herz, Laura M., Scanlon, David O., Walsh, Aron, and Hoye, Robert L. Z.

Published
2022
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21. Welcome to this Brave Bro’s World: the (Re)production of hegemonic masculinity in a Chinese manosphere.

Author

Sun, Luhang and Dai, Linjie

Abstract

Building on a feminist critical discourse analysis, this study reveals the mechanism of the continuous reproduction of hegemonic masculinity in a Chinese manosphere, Hupu, the biggest sports fandom platform in China. As an ideological foundation on Hupu, hegemonic masculinity directs misogynistic practices (e.g. sexualization of women and misogynistic lexicon development) and shapes an imagined community of toxic brotherhood. In turn, the misogynistic practices and this community of brotherhood also reproduce hegemonic masculinity, ensuring a cycle of the maintenance of a toxic manosphere. We further consider the socio-political context in contemporary China to criticize how state power, platform affordances, and hegemonic masculinity are intertwined and jeopardize Chinese feminism both online and offline. [ABSTRACT FROM AUTHOR]

Published
2024
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22. Enhanced Excitonic Nature of MAPbBr3 Nanocrystals in Nanoporous GaN.

Author

Bai, Xinyu, Fairclough, Simon M., Dai, Linjie, Sarkar, Maruf, Griffin, Peter H., Gundimeda, Abhiram, Sun, Yuqi, Greenham, Neil C., Dar, M. Ibrahim, Oliver, Rachel A., and Friend, Richard H.

Subjects
GALLIUM nitride, NANOCRYSTALS, LIGHT emitting diodes, METAL halides, POROUS materials, PEROVSKITE
Abstract

Blue gallium nitride (GaN) light‐emitting diodes (LEDs), combined with red/green fluorescent converters, have broad potential for display applications. Metal halide perovskites now show excellent luminescence properties and may be suitable as light converters. Here a simple solution‐processed method is reported to prepare a methylammonium lead bromide (MAPbBr3) nanoporous GaN composite. Fast (within 2 ps) energy transfer is demonstrated from photoexcited nanoporous GaN to encapsulate MAPbBr3 nanocrystals, as observed by transient absorption spectroscopy. The spatial confinement of the perovskite within the nanoporous GaN is shown to increase the perovskite radiative recombination rate. These results offer guidelines for developing high‐performance perovskite/nanoporous GaN optoelectronics. [ABSTRACT FROM AUTHOR]

Published
2024
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23. Degradation mechanisms of perovskite solar cells under vacuum and one atmosphere of nitrogen

Author

Guo, Renjun, Han, Dan, Chen, Wei, Dai, Linjie, Ji, Kangyu, Xiong, Qiu, Li, Saisai, Reb, Lennart K., Scheel, Manuel A., Pratap, Shambhavi, Li, Nian, Yin, Shanshan, Xiao, Tianxiao, Liang, Suzhe, Oechsle, Anna Lena, Weindl, Christian L., Schwartzkopf, Matthias, Ebert, Hubert, Gao, Peng, Wang, Kai, Yuan, Mingjian, Greenham, Neil C., Stranks, Samuel D., Roth, Stephan V., Friend, Richard H., and Müller-Buschbaum, Peter

Published
2021
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27. High carrier mobility along the [111] orientation in Cu2O photoelectrodes.

Author

Pan, Linfeng, Dai, Linjie, Burton, Oliver J., Chen, Lu, Andrei, Virgil, Zhang, Youcheng, Ren, Dan, Cheng, Jinshui, Wu, Linxiao, Frohna, Kyle, Abfalterer, Anna, Yang, Terry Chien-Jen, Niu, Wenzhe, Xia, Meng, Hofmann, Stephan, Dyson, Paul J., Reisner, Erwin, Sirringhaus, Henning, Luo, Jingshan, and Hagfeldt, Anders

Abstract

Solar fuels offer a promising approach to provide sustainable fuels by harnessing sunlight1,2. Following a decade of advancement, Cu2O photocathodes are capable of delivering a performance comparable to that of photoelectrodes with established photovoltaic materials3–5. However, considerable bulk charge carrier recombination that is poorly understood still limits further advances in performance6. Here we demonstrate performance of Cu2O photocathodes beyond the state-of-the-art by exploiting a new conceptual understanding of carrier recombination and transport in single-crystal Cu2O thin films. Using ambient liquid-phase epitaxy, we present a new method to grow single-crystal Cu2O samples with three crystal orientations. Broadband femtosecond transient reflection spectroscopy measurements were used to quantify anisotropic optoelectronic properties, through which the carrier mobility along the [111] direction was found to be an order of magnitude higher than those along other orientations. Driven by these findings, we developed a polycrystalline Cu2O photocathode with an extraordinarily pure (111) orientation and (111) terminating facets using a simple and low-cost method, which delivers 7 mA cm−2 current density (more than 70% improvement compared to that of state-of-the-art electrodeposited devices) at 0.5 V versus a reversible hydrogen electrode under air mass 1.5 G illumination, and stable operation over at least 120 h.A study introduces a novel method to grow single-crystal Cu2O thin films with selected crystal orientations, highlighting enhanced bulk carrier mobility and carrier diffusion length along the [111] direction that yields Cu2O photocathodes with improved performance. [ABSTRACT FROM AUTHOR]

Published
2024
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29. Fast Near‐Infrared Photodetectors Based on Nontoxic and Solution‐Processable AgBiS2

Author

Huang, Yi‐Teng, primary, Nodari, Davide, additional, Furlan, Francesco, additional, Zhang, Youcheng, additional, Rusu, Marin, additional, Dai, Linjie, additional, Andaji‐Garmaroudi, Zahra, additional, Darvill, Daniel, additional, Guo, Xiaoyu, additional, Rimmele, Martina, additional, Unold, Thomas, additional, Heeney, Martin, additional, Stranks, Samuel D., additional, Sirringhaus, Henning, additional, Rao, Akshay, additional, Gasparini, Nicola, additional, and Hoye, Robert L. Z., additional

Published
2023
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30. Author Correction: Degradation mechanisms of perovskite solar cells under vacuum and one atmosphere of nitrogen

Author

Guo, Renjun, Han, Dan, Chen, Wei, Dai, Linjie, Ji, Kangyu, Xiong, Qiu, Li, Saisai, Reb, Lennart K., Scheel, Manuel A., Pratap, Shambhavi, Li, Nian, Yin, Shanshan, Xiao, Tianxiao, Liang, Suzhe, Oechsle, Anna Lena, Weindl, Christian L., Schwartzkopf, Matthias, Ebert, Hubert, Gao, Peng, Wang, Kai, Yuan, Mingjian, Greenham, Neil C., Stranks, Samuel D., Roth, Stephan V., Friend, Richard H., and Müller-Buschbaum, Peter

Published
2022
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32. Tailoring Interlayer Charge Transfer Dynamics in 2D Perovskites with Electroactive Spacer Molecules

Author

Boeije, Yorrick, primary, Van Gompel, Wouter T. M., additional, Zhang, Youcheng, additional, Ghosh, Pratyush, additional, Zelewski, Szymon J., additional, Maufort, Arthur, additional, Roose, Bart, additional, Ooi, Zher Ying, additional, Chowdhury, Rituparno, additional, Devroey, Ilan, additional, Lenaers, Stijn, additional, Tew, Alasdair, additional, Dai, Linjie, additional, Dey, Krishanu, additional, Salway, Hayden, additional, Friend, Richard H., additional, Sirringhaus, Henning, additional, Lutsen, Laurence, additional, Vanderzande, Dirk, additional, Rao, Akshay, additional, and Stranks, Samuel D., additional

Published
2023
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35. High anisotropy in electrical and thermal conductivity through the design of aerogel-like superlattice (NaOH)0.5NbSe2.

Author

Sun, Ruijin, Deng, Jun, Wu, Xiaowei, Hao, Munan, Ma, Ke, Ma, Yuxin, Zhao, Changchun, Meng, Dezhong, Ji, Xiaoyu, Ding, Yiyang, Pang, Yu, Qian, Xin, Yang, Ronggui, Li, Guodong, Li, Zhilin, Dai, Linjie, Ying, Tianping, zhao, Huaizhou, Du, Shixuan, and Li, Gang

Subjects
THERMAL conductivity, ELECTRIC conductivity, HEAT capacity, ANISOTROPY, TRANSITION temperature, SUPERCONDUCTING transition temperature, SUPERLATTICES
Abstract

Interlayer decoupling plays an essential role in realizing unprecedented properties in atomically thin materials, but it remains relatively unexplored in the bulk. It is unclear how to realize a large crystal that behaves as its monolayer counterpart by artificial manipulation. Here, we construct a superlattice consisting of alternating layers of NbSe2 and highly porous hydroxide, as a proof of principle for realizing interlayer decoupling in bulk materials. In (NaOH)0.5NbSe2, the electric decoupling is manifested by an ideal 1D insulating state along the interlayer direction. Vibration decoupling is demonstrated through the absence of interlayer models in the Raman spectrum, dominant local modes in heat capacity, low interlayer coupling energy and out-of-plane thermal conductivity (0.28 W/mK at RT) that are reduced to a few percent of NbSe2's. Consequently, a drastic enhancement of CDW transition temperature (>110 K) and Pauling-breaking 2D superconductivity is observed, suggesting that the bulk crystal behaves similarly to an exfoliated NbSe2 monolayer. Our findings provide a route to achieve intrinsic 2D properties on a large-scale without exfoliation. Interlayer decoupling plays an essential role in realizing unprecedented properties. Here, authors construct a superlattice consisting of alternating layers of NbSe2 and highly porous hydroxide, realizing interlayer decoupling and thus realizing exotic monolayer behaviors in bulk materials. [ABSTRACT FROM AUTHOR]

Published
2023
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37. Elucidating the Role of Antisolvents on the Surface Chemistry and Optoelectronic Properties of CsPbBrxI3-x Perovskite Nanocrystals

Author

Ye, Junzhi, primary, Li, Zhenchao, additional, Kubicki, Dominik J., additional, Zhang, Yunwei, additional, Dai, Linjie, additional, Otero-Martínez, Clara, additional, Reus, Manuel A., additional, Arul, Rakesh, additional, Dudipala, Kavya Reddy, additional, Andaji-Garmaroudi, Zahra, additional, Huang, Yi-Teng, additional, Li, Zewei, additional, Chen, Ziming, additional, Müller-Buschbaum, Peter, additional, Yip, Hin-Lap, additional, Stranks, Samuel D., additional, Grey, Clare P., additional, Baumberg, Jeremy J., additional, Greenham, Neil C., additional, Polavarapu, Lakshminarayana, additional, Rao, Akshay, additional, and Hoye, Robert L. Z., additional

Published
2022
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38. Influence of Halide Choice on Formation of Low‐Dimensional Perovskite Interlayer in Efficient Perovskite Solar Cells

Author

Liu, Xueping, primary, Webb, Thomas, additional, Dai, Linjie, additional, Ji, Kangyu, additional, Smith, Joel A., additional, Kilbride, Rachel C., additional, Yavari, Mozhgan, additional, Bi, Jinxin, additional, Ren, Aobo, additional, Huang, Yuanyuan, additional, Wang, Zhuo, additional, Shen, Yonglong, additional, Shao, Guosheng, additional, Sweeney, Stephen J., additional, Hinder, Steven, additional, Li, Hui, additional, Lidzey, David G., additional, Stranks, Samuel D., additional, Greenham, Neil C., additional, Silva, S. Ravi P., additional, and Zhang, Wei, additional

Published
2022
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39. Anchoring of halogen-cleaved organic ligands on perovskite surfaces

Author

Hu, Juntao, primary, Chen, Peng, additional, Luo, Deying, additional, Dai, Linjie, additional, Chen, Nan, additional, Li, Shunde, additional, Yang, Shiyu, additional, Fu, Zewei, additional, Wang, Dengke, additional, Gong, Qihuang, additional, Stranks, Samuel D., additional, Zhu, Rui, additional, and Lu, Zheng-Hong, additional

Published
2022
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42. Efficient and Spectrally Stable Blue Perovskite Light-Emitting Diodes Employing a Cationic π-Conjugated Polymer

Author

Yuan, Shuai, Cui, Lin-Song, Dai, Linjie, Liu, Yun, Liu, Qing-Wei, Sun, Yu-Qi, Auras, Florian, Anaya, Miguel, Zheng, Xiaopeng, Ruggeri, Edoardo, Yu, You-Jun, Qu, Yang-Kun, Abdi-Jalebi, Mojtaba, Bakr, Osman M, Wang, Zhao-Kui, Stranks, Samuel D, Greenham, Neil C, Liao, Liang-Sheng, Friend, Richard H, Cui, Lin-Song [0000-0001-6577-3432], and Apollo - University of Cambridge Repository

Subjects
ion migrations, blue emissions, high efficiencies, stabilities, perovskite light-emitting diodes
Abstract

Metal halide perovskite semiconductors have demonstrated remarkable potentials in solution-processed blue light-emitting diodes (LEDs). However, the unsatisfied efficiency and spectral stability responsible for trap-mediated non-radiative losses and halide phase segregation remain the primary unsolved challenges for blue perovskite LEDs. In this study, it is reported that a fluorene-based π-conjugated cationic polymer can be blended with the perovskite semiconductor to control film formation and optoelectronic properties. As a result, sky-blue and true-blue perovskite LEDs with Commission Internationale de l'Eclairage coordinates of (0.08, 0.22) and (0.12, 0.13) at the record external quantum efficiencies of 11.2% and 8.0% were achieved. In addition, the mixed halide perovskites with the conjugated cationic polymer exhibit excellent spectral stability under external bias. This result illustrates that π-conjugated cationic polymers have a great potential to realize efficient blue mixed-halide perovskite LEDs with stable electroluminescence.

Published
2021

44. Understanding the Role of Grain Boundaries on Charge‐Carrier and Ion Transport in Cs 2 AgBiBr 6 Thin Films

Author

Li, Zewei, Senanayak, Satyaprasad P., Dai, Linjie, Kusch, Gunnar, Shivanna, Ravichandran, Zhang, Youcheng, Pradhan, Dipika, Ye, Junzhi, Huang, Yi‐Teng, Sirringhaus, Henning, Oliver, Rachel A., Greenham, Neil C., Friend, Richard H., Hoye, Robert L. Z., Senanayak, Satyaprasad P. [0000-0002-8927-685X], Sirringhaus, Henning [0000-0001-9827-6061], Greenham, Neil C. [0000-0002-2155-2432], Friend, Richard H. [0000-0001-6565-6308], Hoye, Robert L. Z. [0000-0002-7675-0065], and Apollo - University of Cambridge Repository

Subjects
ComputingMilieux_GENERAL, ion migration, lead‐free double perovskites, thin film transistors, ComputingMilieux_COMPUTERSANDEDUCATION, ComputingMilieux_COMPUTERSANDSOCIETY, carrier mobilities, grain boundaries, GeneralLiterature_MISCELLANEOUS, ComputingMilieux_MISCELLANEOUS, Research Articles, Research Article
Abstract

Funder: Cambridge Trust and Chinese Scholarship, Funder: Royal Academy of Engineering; Id: http://dx.doi.org/10.13039/501100000287, Halide double perovskites have gained significant attention, owing to their composition of low‐toxicity elements, stability in air, and recent demonstrations of long charge‐carrier lifetimes that can exceed 1 µs. In particular, Cs2AgBiBr6 is the subject of many investigations in photovoltaic devices. However, the efficiencies of solar cells based on this double perovskite are still far from the theoretical efficiency limit of the material. Here, the role of grain size on the optoelectronic properties of Cs2AgBiBr6 thin films is investigated. It is shown through cathodoluminescence measurements that grain boundaries are the dominant nonradiative recombination sites. It also demonstrates through field‐effect transistor and temperature‐dependent transient current measurements that grain boundaries act as the main channels for ion transport. Interestingly, a positive correlation between carrier mobility and temperature is found, which resembles the hopping mechanism often seen in organic semiconductors. These findings explain the discrepancy between the long diffusion lengths >1 µm found in Cs2AgBiBr6 single crystals versus the limited performance achieved in their thin film counterparts. This work shows that mitigating the impact of grain boundaries will be critical for these double perovskite thin films to reach the performance achievable based on their intrinsic single‐crystal properties.

Published
2021

45. Efficient and Spectrally Stable Blue Perovskite Light‐Emitting Diodes Employing a Cationic π‐Conjugated Polymer

Author

Yuan, Shuai, primary, Cui, Lin‐Song, additional, Dai, Linjie, additional, Liu, Yun, additional, Liu, Qing‐Wei, additional, Sun, Yu‐Qi, additional, Auras, Florian, additional, Anaya, Miguel, additional, Zheng, Xiaopeng, additional, Ruggeri, Edoardo, additional, Yu, You‐Jun, additional, Qu, Yang‐Kun, additional, Abdi‐Jalebi, Mojtaba, additional, Bakr, Osman M., additional, Wang, Zhao‐Kui, additional, Stranks, Samuel D., additional, Greenham, Neil C., additional, Liao, Liang‐Sheng, additional, and Friend, Richard H., additional

Published
2021
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46. Understanding the Role of Grain Boundaries on Charge‐Carrier and Ion Transport in Cs2AgBiBr6 Thin Films

Author

Li, Zewei, primary, Senanayak, Satyaprasad P., additional, Dai, Linjie, additional, Kusch, Gunnar, additional, Shivanna, Ravichandran, additional, Zhang, Youcheng, additional, Pradhan, Dipika, additional, Ye, Junzhi, additional, Huang, Yi‐Teng, additional, Sirringhaus, Henning, additional, Oliver, Rachel A., additional, Greenham, Neil C., additional, Friend, Richard H., additional, and Hoye, Robert L. Z., additional

Published
2021
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47. Strong absorption and ultrafast localisation in NaBiS2 nanocrystals with slow charge-carrier recombination.

Author

Huang, Yi-Teng, Kavanagh, Seán R., Righetto, Marcello, Rusu, Marin, Levine, Igal, Unold, Thomas, Zelewski, Szymon J., Sneyd, Alexander J., Zhang, Kaiwen, Dai, Linjie, Britton, Andrew J., Ye, Junzhi, Julin, Jaakko, Napari, Mari, Zhang, Zhilong, Xiao, James, Laitinen, Mikko, Torrente-Murciano, Laura, Stranks, Samuel D., and Rao, Akshay

Subjects
NANOCRYSTALS, ABSORPTION coefficients, VALENCE bands, DENSITY of states, PHOTOCONDUCTIVITY, ELECTRIC charge, ABSORPTION
Abstract

I-V-VI2 ternary chalcogenides are gaining attention as earth-abundant, nontoxic, and air-stable absorbers for photovoltaic applications. However, the semiconductors explored thus far have slowly-rising absorption onsets, and their charge-carrier transport is not well understood yet. Herein, we investigate cation-disordered NaBiS2 nanocrystals, which have a steep absorption onset, with absorption coefficients reaching >105 cm−1 just above its pseudo-direct bandgap of 1.4 eV. Surprisingly, we also observe an ultrafast (picosecond-time scale) photoconductivity decay and long-lived charge-carrier population persisting for over one microsecond in NaBiS2 nanocrystals. These unusual features arise because of the localised, non-bonding S p character of the upper valence band, which leads to a high density of electronic states at the band edges, ultrafast localisation of spatially-separated electrons and holes, as well as the slow decay of trapped holes. This work reveals the critical role of cation disorder in these systems on both absorption characteristics and charge-carrier kinetics. Ternary chalcogenides are gaining interest as nontoxic, stable solar absorbers. Here, the authors investigate NaBiS2, finding cation disorder to be a critical parameter that enables its high absorption strength and unusual charge-carrier kinetics. [ABSTRACT FROM AUTHOR]

Published
2022
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48. Elucidating the Role of Antisolvents on the Surface Chemistry and Optoelectronic Properties of CsPbBrxI3‑x Perovskite Nanocrystals.

Author

Ye, Junzhi, Li, Zhenchao, Kubicki, Dominik J., Zhang, Yunwei, Dai, Linjie, Otero-Martínez, Clara, Reus, Manuel A., Arul, Rakesh, Dudipala, Kavya Reddy, Andaji-Garmaroudi, Zahra, Huang, Yi-Teng, Li, Zewei, Chen, Ziming, Müller-Buschbaum, Peter, Yip, Hin-Lap, Stranks, Samuel D., Grey, Clare P., Baumberg, Jeremy J., Greenham, Neil C., and Polavarapu, Lakshminarayana

Published
2022
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50. Understanding the Role of Grain Boundaries on Charge‐Carrier and Ion Transport in Cs2AgBiBr6 Thin Films.

Author

Li, Zewei, Senanayak, Satyaprasad P., Dai, Linjie, Kusch, Gunnar, Shivanna, Ravichandran, Zhang, Youcheng, Pradhan, Dipika, Ye, Junzhi, Huang, Yi‐Teng, Sirringhaus, Henning, Oliver, Rachel A., Greenham, Neil C., Friend, Richard H., and Hoye, Robert L. Z.

Subjects
CRYSTAL grain boundaries, THIN films, SOLAR cell efficiency, ION channels, ORGANIC semiconductors, TRP channels
Abstract

Halide double perovskites have gained significant attention, owing to their composition of low‐toxicity elements, stability in air, and recent demonstrations of long charge‐carrier lifetimes that can exceed 1 µs. In particular, Cs2AgBiBr6 is the subject of many investigations in photovoltaic devices. However, the efficiencies of solar cells based on this double perovskite are still far from the theoretical efficiency limit of the material. Here, the role of grain size on the optoelectronic properties of Cs2AgBiBr6 thin films is investigated. It is shown through cathodoluminescence measurements that grain boundaries are the dominant nonradiative recombination sites. It also demonstrates through field‐effect transistor and temperature‐dependent transient current measurements that grain boundaries act as the main channels for ion transport. Interestingly, a positive correlation between carrier mobility and temperature is found, which resembles the hopping mechanism often seen in organic semiconductors. These findings explain the discrepancy between the long diffusion lengths >1 µm found in Cs2AgBiBr6 single crystals versus the limited performance achieved in their thin film counterparts. This work shows that mitigating the impact of grain boundaries will be critical for these double perovskite thin films to reach the performance achievable based on their intrinsic single‐crystal properties. [ABSTRACT FROM AUTHOR]

Published
2021
Full Text
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