浙江大学研究人员在高电流密度下明亮稳定的红色钙钛矿LED研究上取得新突破
钙钛矿LEDs(PeLEDs)已经成为下一代发光技术。最近，浙江大学狄大卫/赵保丹CEJ在实现高稳定的近红外和绿色发光二极管方面取得了突破。然而，在高电流密度(>10 mA cm-2)下，可见PeLEDs的工作寿命(T50)仍然不令人满意(通常<100小时)，限制了固态照明和AR/VR应用的可能性。对于混合卤化物(例如，红色和蓝色)钙钛矿发射器，这个问题变得更加明显，其中存在卤化物偏析和光谱不稳定等关键挑战。在这里，他们展示了基于混合卤化物钙钛矿的明亮和稳定的红色PeLEDs，在≥25 mA cm-2的电流下，T50寿命可达~ 357小时，这是高电流密度下可见pled运行稳定性的记录。该器件产生强烈而稳定的发射，最大亮度为28,870 cd m-2(辐射度:1584 W sr-1 m-2)，这是红色PeLEDs的最高记录。该演示的关键是引入了磺胺，这是一种偶极分子稳定剂，可以有效地与钙钛矿发射体中的离子相互作用。它抑制卤化物偏析和迁移到电荷输运层，从而提高了混合卤化物PeLEDs的稳定性和亮度。这些结果代表着朝着明亮和稳定的PeLEDs的新兴应用迈出了重要的一步。Figure 1. Photo- and thermal stability of the perovskite samples. (a) PL measurements for the control sample under a 405 nm pulsed laser excitation (∼80 μJ cm–2, 50 kHz) in air. (b) Microscopic imaging of the PL peak wavelength for the as-prepared and aged control samples after 15 min of a 405 nm c.w. laser irradiation (∼135 μJ cm–2, 50 kHz) in air. (c) PL measurements for the SFA-stabilized sample under a 405 nm pulsed laser excitation (∼80 μJ cm–2, 50 kHz) in air. (d) Microscopic imaging of the PL peak wavelength for as-prepared and aged SFA-stabilized samples after 15 min of a 405 nm c.w. laser irradiation (∼135 μJ cm–2, 50 kHz) in air. (e) X-ray diffraction (XRD) patterns of the control samples at an annealing temperature of 100 °C for different time durations. (f) XRD patterns of SFA-stabilized samples under an annealing temperature of 100 °C for different time durations.Figure 2. Characterization of chemical interactions. (a) Molecular structures of SFA and its structurally related molecules BSA, BDA, and BA. (b) 1H NMR spectra of FABr, FABr:BA, FABr:BDA, FABr:BSA, and FABr:SFA solutions. (c) 1H NMR spectra of BA, BA:PbI2, BDA, and BDA:PbI2. (d) 1H NMR spectra of BSA, BSA:PbI2, SFA, and SFA:PbI2. (e) 1I NMR spectra of CsI, CsI:BA, CsI:BDA, CsI:BSA, and CsI:SFA. (f) XPS spectra of the Pb 4f peaks for the control, BA-, BDA-, BSA-, and SFA-based samples. (g) XPS spectra of the I 3d peaks for the samples. (h) XPS spectra of the Br 3d peaks for the samples.Figure 3. Device performance with operational stability. (a) Schematic device architecture. (b) EL spectra of the FA0.5Cs0.5PbI2Br (control), FA0.5Cs0.5PbI2Br:SFA (peak wavelength: 683 nm), and FA0.5Cs0.5PbI2.75Br0.25:SFA (peak wavelength: 710 nm) devices. (c) Current density–voltage curves. (d) Current density–luminance curves. (e) Current density–radiance curves. (f) EQE–current density curves of the as-fabricated devices. (g) Operational lifetime tests for the FA0.5Cs0.5PbI2Br (control) and SFA-stabilized FA0.5Cs0.5PbI2Br devices were performed under a constant current density of 25 mA cm–2. (h) Lifetime tests for FA0.5Cs0.5PbI2Br:SFA devices under constant current densities of 25, 50, 100, 200, and 400 mA cm–2. (i) T50 lifetime records for visible PeLEDs plotted against current densities. The T50 data of PeLEDs reported in this work were obtained from direct measurements.Figure 4. Further characterizations of PeLEDs. (a) Current density–voltage characteristics for the control PeLEDs. The forward and reverse scans (100 cycles) were recorded at a scan rate of 0.1 V s–1. (b) Current density–voltage characteristics for SFA-stabilized PeLEDs. The forward and reverse scans (100 cycles) were recorded at a scan rate of 0.1 V s–1. (c) TOF-SIMS depth profiling was performed for the as-prepared and aged control PeLED devices. Panel (d) demonstrates TOF-SIMS depth profiling for the as-prepared and aged SFA-stabilized PeLEDs.来源：发光材料与器件
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