Zn-Alloyed CsPbI₃ Nanocrystals for Highly Efficient Perovskite Light-Emitting Devices

Abstract

We alloyed Zn2+ into CsPbI3 perovskite nanocrystals by partial substitution of Pb2+ with Zn2+, which does not change their crystalline phase. The resulting alloyed CsPb0.64Zn0.36I3 nanocrystals exhibited an improved, close-to-unity photoluminescence quantum yield of 98.5% due to the increased radiative decay rate and the decreased non-radiative decay rate. They also showed an enhanced stability, which correlated with improved effective Goldschmidt tolerance factors, by the incorporation of Zn2+ ions with a smaller radius than the Pb2+ ions. Simultaneously, the nanocrystals switched from n-type (for CsPbI3) to nearly ambipolar for the alloyed nanoparticles. The hole injection barrier of electroluminescent LEDs was effectively eliminated by using alloyed CsPb0.64Zn0.36I3 nanocrystals, and a high peak external quantum efficiency of 15.1% has been achieved.

Energy Level Modification with Carbon Dot Interlayers Enables Efficient Perovskite Solar Cells and Quantum Dot Based Light‐Emitting Diodes

“…Energy level values for CsPbI 3 QD, TCTA, and MoO 3 /Au were taken from ref. Figure 5c shows TEM image of CsPbI 3 QDs, which are monodisperse cubic‐shaped particles with an edge length of 10–12 nm and an interplanar distance of 0.62 nm consistent with the (100) plane of cubic CsPbI 3 . The CBM of ZnO increases from −3.96 to −3.78 eV as a result of the CD 0.33 modification, placing it higher than the lowest unoccupied molecular orbital of CsPbI 3 QDs, offering a barrier to prevent electrons transfer from CsPbI 3 QD emitting layer to ZnO ETL.…”

Metal halide perovskite nanocrystals and their applications in optoelectronic devices

“…Monodisperse CsPbBr 3 nanorods (NRs) were synthesized by hot injection by Yang et al and LEDs were prepared with a structure of ITO/PEDOT:PSS/TFB/CsPbBr 3 NRs/TPBi/LiF/Al, which is one of the best performances of CsPbBr 3 NC‐based LEDs so far (EQE = 8.2%) . Shen and coworkers adopted Zn 2+ doping to synthesize CsPbI 3 NCs and used them as the EML to increase the EQE of red NC LEDs to 15.1% . In addition, blue perovskite NC LEDs have an EQE over 2% …”

“…216 Shen and coworkers adopted Zn 2+ doping to synthesize CsPbI 3 NCs and used them as the EML to increase the EQE of red NC LEDs to 15.1%. 198 In addition, blue perovskite NC LEDs have an EQE over 2%. 217 Even though the synthetic method of perovskite NCs is becoming more mature, and the perovskite NC LEDs have undergone an impressive development in recent years, there is still a device efficiency gap compared with organic light-emitting diodes (OLEDs) and quantum dot light-emitting diodes (QLEDs).…”

Metal Doping/Alloying of Cesium Lead Halide Perovskite Nanocrystals and their Applications in Light‐Emitting Diodes with Enhanced Efficiency and Stability

“…Further increasing the alloying ratio to 0.49 resulted in a decreased PLQY to 78 %, which was due to the increased defect density or a possible increase in the dark fraction of emitters at higher Zn contents. [65] In a recent work, Li et al employed a post-treatment method of the perovskite NCs employing Zn halide salt/ hexane solution achieved significantly increased PLQY of the CsPbX 3 NCs, boosting the optimum PLQYs to 86, 93, and 95 % for CsPbCl 3 , CsPbBr 3 and CsPbI 3 NCs, respectively. [66] Interestingly, unlike the previous demonstrated Zn 2 + doping, which exhibited obvious blue-shift of the PL emission, no change in the PL emission peaks were observed, which suggested that the post treatment might only affect the surface of the perovskite NCs.…”

“…Reproduced with permission. [65] Copyright © 2019 American Chemical Society. (e) Absorbance and PL spectra of CsPbCl 3 NC with Ni 2 + doping concentration, the inset images are of NC colloidal solution under UV irradiation (f) PL decay of Ni 2 + doped CsPbCl 3 NC.…”