河南科技大学考研，河南科技大学考研分数线
近年来，钙钛矿材料因其优异的光电性能受到研究者的密切关注，已被广泛应用于发光二极管、太阳能电池、光电探测器等光电子领域。目前PeLED的外量子效率（EQE）已接近30%，这使得PeLED成为商业照明和显示领域的优秀候选者。尽管EQE取得了大的进步，但是钙钛矿的稳定性仍是研究者们正在极力解决的问题。全无机PeLED相对于有机无机杂化PeLED有更好的稳定性，但为了实现各功能层之间能带匹配，报道的全无机PeLED中电荷传输层也多为有机材料（如：TPBi、PEDOT:PSS等），实现整个器件结构为全无机的研究非常有限。
鉴于此，2023年4月1日河南科技大学王辉/赵洋团队于Ceramics International刊发题为《Vacuum-deposited perovskite CsPbBr3 thin-films for temperature-stable Si based pure-green all-inorganic light-emitting diodes》的研究论文。通过真空热蒸发法和磁控溅射技术成功制备p-NiO/CsPbBr3/n-Si硅基全无机结构绿色PeLED。该PeLED实现了发射峰位于527 nm处的绿色发射（EL半峰宽18 nm），其具有较宽的色域，达到CIE1931 NTSC标准的~114%。进一步对该全无机结构PeLED的热稳定性进行了研究（温度范围为RT – 110℃），令人兴奋的是，该全无机结构二极管表现出高达80℃的温度稳定性和色稳定性，即使在110℃的高工作温度下，该二极管的发光强度仍能保持在初始强度的90%以上。
特别是对二极管进行了热循环试验（30℃到100℃），经过7次循环试验，PeLED的发射强度几乎可以恢复到初始水平。进一步，通过第一性原理计算证实了CsPbBr3晶体结构在~84℃发生的相转变（由正交相转变为四方相）是该PeLED温度稳定性达80℃的主要内在原因。该工作为推进PeLED实用化做出了有效探索。
Fig. 1. (a) The schematic diagram of dual-source co-evaporation deposition for CsPbBr3film. (b) The Rietveld refinement of the CsPbBr3. (c) Optical absorption and PL spectra of the CsPbBr3 film. (d) The surface SEM image of CsPbBr3 film prepared by the thermally evaporated. (e) Grain size distribution of CsPbBr3 film. (f) The (αhν)2~hν relationship used for the bandgap estimation.
Fig. 2. (a) PL spectra of CsPbBr3 film measured at different temperatures from 10K to 210 K. (b) Gaussian fits of three PL spectra measured at 10, 90, and 170 K. (c) Two mechanisms of carrier recombination in CsPbBr3films at low temperature. (d) Dependence of PL strength of CsPbBr3film on the reciprocal of ambient temperature. (e) Investigated the temperature dependence of PL FWHM. (f) PL radiative recombination rate of CsPbBr3film at different temperatures.
Fig. 3. (a) Schematic diagram of the p-NiO/CsPbBr3/n-Si all-inorganic PeLED preparation process and structure. (b) Cross-sectional SEM image for the PeLED structure. (c) Current versus voltage characteristics of the PeLED, the inset shows the lnI-V curve of the PeLED. (d) Calculated the series resistance of the PeLED through the I/(dI/dV)~I relationship. (e) The lnI-lnV relationship of the PeLED.
Fig. 4. (a) Luminance as a function of current density for the PeLED, the inset shows the maximum luminance distribution statistics of 25 devices. (b) Luminance-EQE-Current efficiency of the PeLED. (c) Comparison of normalized PL and EL spectra. (d) The EL spectra of PeLED operated at various currents. (e) The EL intensity of the PeLED varies with the injection current. (f) EL spectra evolution under 3 mA, the inset shows the change of EL intensity with time. (g) CIE color coordinate of the PeLED at 8 mA. (h) Overall energy band diagram of the proposed PeLED structure. (i) EI~ICm, characteristics of the PeLED in a log-log scale.
Fig. 5. (a) The EL spectra of the PeLED at different ambient temperatures (applied current was 8 mA). (b) Pseudocolor map of temperature-dependent EL spectra of the PeLED ranging from 40 to 110℃. (c) Variation of EL intensity with ambient temperature (at 6 mA and 8 mA). (d) The relationship between FWHM and temperature. (e) First-principles calculations of the crystal structure stability for the orthorhombic and tetragonal phases of CsPbBr3. (f) The crystal structures of CsPbBr3 orthorhombic and tetragonal phases. (g) The heating/cooling cycles show the dependence of EL intensity on temperature. (h) Investigating the influence of ambient temperature on the color stability of the PeLED, the insets show the corresponding chromaticity diagrams.
G. Xiang, Y. Zhou, W. Peng, J. Zhang, Y. Liu, J. Zhang, Z. Yue, X. Zhang, C. Song, B. Ding, Y. Jin, P. Wang, H. Wang, Y. Zhao, Vacuum-deposited perovskite CsPbBr3 thin-films for temperature-stable Si based pure-green all-inorganic light-emitting diodes, Ceramics International (2023)
DOI: 10.1016/j.ceramint.2023.03.298
https://doi.org/10.1016/j.ceramint.2023.03.298
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河南科技大学考研(河南科技大学考研分数线)