Browsing by Author "Xu, Yubing"

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    Bismuth-doping induced red-shifted spectral response of homo-epitaxial MAPbBr3 photodiodes
    (American Institute of Physics, 2023) Xu, Yubing; Wang, Xin; Pan, Yuzhu; Chai, ShunJie; Wu, Jie; Wang, Mengrou; Perveen, Abida; Onwudiwe, Damian Chinedu; Talaighil, Razika Zair; Bae, Byung Seong; Zhu, Ying; Chen, Jing; Lei, Wei
    Perovskite single crystals (PSCs) photodiodes with p-n junctions have been widely studied due to their effective blocking of injected current with barriers and quickly separating the electrons and hole pairs with a built-in electric field. Here, we report a solution-processed epitaxial (SPE) growth method to fabricate p-n photodiodes based on MAPbBr3 PSCs. In the structure of the MAPbBr3 PSCs, bismuth donor doping will change the conduction type from p-type to n-type and redshift the absorption edge along with the increase in Bi concentration. Therefore, this work successfully fabricates the p-n photodiodes with homo-epitaxial Bi-doped (n-type) MAPbBr3 layers grown on the surface of undoped (p-type) MAPbBr3 PSCs substrates through the SPE growth method. The p-n photodiodes achieve a tunable spectral response by simply adjusting the Bi doping concentrations of homo-epitaxial MAPbBr3 layers. The spectral response peaks redshift from 559 to 601 nm, with an increasing Bi doping level of 0% to 15%.
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    Enhanced nanogenerator by embedding lead-free double perovskite Cs2AgBiBr6 in polymer matrix for hybrid energy harvesting
    (Royal Society of Chemistry, 2023) Wang, Mengrou; Wang, Xin; Xu, Yubing; Chai, Shunjie; Zhao, Zhiwei; Li, Qing; Wu, Jun; Chen, Jing; Zhu, Zhuoya; Bae, Byung Seong; Tala-Ighil, Razika; Zhou, Jianming
    Mechanical energy harvesters fabricated with halide perovskites display excellent electrical output because of their prominent permittivity. An all-inorganic lead-free double perovskite, Cs2AgBiBr6 (CABB), with competitive performance, excellent environmental stability and non-toxicity can break the confines of practical unavailability. CABB microcrystals, which are effective nucleating agents and dielectric fillers, are embedded into a polyvinylidene-fluoride (PVDF)-matrix as efficient electron-acceptors to induce electro-active PVDF β-phase formation and enhance the composite dielectric constant, which contributes to notable hybrid electric outputs. CABB-PVDF hybrid nanogenerators with the optimal CABB concentration of 20 wt% possess triboelectric and piezoelectric effects, with a nanogenerator with a 1.2 cm × 1.2 cm effective contact area and 70 μm film thickness exhibiting a unique response with an open-circuit voltage of 126 V and a short-current density of 4.67 mA m−2 under a 0.5 Hz mechanical frequency and 4 cm s−1 motion speed. An identical device achieves the highest output power density of 0.39 W m−2 at 8 Hz and 0.64 m s−1, which could light up at least 86 commercial LEDs using a 1 μF capacitor and power small electronic devices such as a timer using 22 μF. The corresponding force sensing is achieved with a different distribution of external forces using a 10 wt% CABB-PVDF composite film. This functional composite maintains its stability and charge retention capacity for effective application in various environmental conditions.
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    Sensitive thermography via sensing visible photons detected from the manipulation of the trap state in MAPbX3
    (American Chemical Society, 2023) Xu, Yubing; Wang, Xin; Liu, Shilin; Pan, Yuzhu; Perveen, Abida; Onwudiwe, Damian Chinedu; Fayemi, Omolola Esther; Elemike, Elias Emeka; Bae, Byung Seong; Zhu, Ying; Talaighil, Razika Zair; Zhang, Xiaobing; Chen, Jing; Zhao, Zhiwei; Li, Qing; Lei, Wei; Xu, Xiaobao
    Sensitive thermometry or thermography by responding to blackbody radiation is urgently desired in the intelligent information life, including scientific research, medical diagnosis, remote sensing, defense, etc. Even though thermography techniques based on infrared sensing have undergone unprecedented development, the poor compatibility with common optical components and the high diffraction limit impose an impediment to their integration into the established photonic integrated circuit or the realization of high-spatial-resolution and high-thermal-resolution imaging. In this work, we present a sensitive temperature-dependent visible photon detection in Bi-doped MAPbX3 (X = Cl, Br, and I) and employ it for uncooled thermography. Systematic measurements reveal that the Bi dopant introduces trap states in MAPbX3, thermal energy facilitates the carriers jumping from trap states to the conduction band, while the vacancies of trap states ensure the sequential absorption of visible photons with energy less than the band gap. Subsequently, the change of response toward the visible photon is applied to construct the thermograph, and it possesses a specific sensitivity of 2.11% K–1 along temperature variation. As a result, our thermograph presents a temperature resolution of 0.21 nA K–1, a high responsivity of 2.06 mA W–1, and a high detectivity of 2.08 × 109 Jones at room temperature. Furthermore, remote thermal imaging is successfully achieved with our thermograph.