Ce³⁺-Doping to Modulate Photoluminescence Kinetics for Efficient CsPbBr₃ Nanocrystals Based Light-Emitting Diodes

Abstract

Inorganic perovskite CsPbBr nanocrystals (NCs) are emerging, highly attractive light emitters with high color purity and good thermal stability for light-emitting diodes (LEDs). Their high photo/electroluminescence efficiencies are very important for fabricating efficient LEDs. Here, we propose a novel strategy to enhance the photo/electroluminescence efficiency of CsPbBr NCs through doping of heterovalent Ce ions via a facile hot-injection method. The Ce cation was chosen as the dopant for CsPbBr NCs by virtue of its similar ion radius and formation of higher energy level of conduction band with bromine in comparison with the Pb cation to maintain the integrity of perovskite structure without introducing additional trap states. It was found that by increasing the doping amount of Ce in CsPbBr NCs to 2.88% (atomic percentage of Ce compared to Pb) the photoluminescence quantum yield (PLQY) of CsPbBr NCs reached up to 89%, a factor of 2 increase in comparison with the native, undoped ones. The ultrafast transient absorption and time-resolved photoluminescence (PL) spectroscopy revealed that Ce-doping can significantly modulate the PL kinetics to enhance the PL efficiency of doped CsPbBr NCs. As a result, the LED device fabricated by adopting Ce-doped CsPbBr NCs as the emitting layers exhibited a pronounced improvement of electroluminescence with external quantum efficiency (EQE) from 1.6 to 4.4% via Ce-doping.

Yb3+ and Yb3+/Er3+ doping for near-infrared emission and improved stability of CsPbCl3 nanocrystals

“…According to the Burstein–Moss effect in heavily doped n-type semiconductors, slight blue shifts of both absorption and PL positions can be attributed to the filling of the state by the donated electrons of Yb 3+ around the bottom of the conduction band, which leads to some band gap widening. 41 Their powder XRD patterns confirmed that their crystal structure still adopts the tetragonal phase (JCPDS No. PDF#18–0366) with the space group P4mm (Fig.…”

Recent advances and prospects toward blue perovskite materials and light‐emitting diodes

“…As typical defect‐tolerant materials, doping is an effective strategy to produce perovskites with high PL efficiencies and stability, and suitable electrical properties . Hence, the stability and PLQY are obviously enhanced by reducing the defect state density and passivating grain boundaries, leading to excellent optoelectronic properties for devices constructed by using the doped perovskites as active layers . Typically, various metal ions, including Bi 3+ , Ni 2+ , Mn 2+ , Cu 2+ , Zn 2+ , Cd 2+ and rare earth ions (eg, Ce 3+ , Er 3+ , Yb 3+ ), have been doped into halide perovskites.…”

“…63 Copyright 2018 American Chemical Society optoelectronic properties for devices constructed by using the doped perovskites as active layers. [78][79][80][81][82] Typically, various metal ions, including Bi 3+ , Ni 2+ , Mn 2+ , Cu 2+ , Zn 2+ , Cd 2+46,48,50,83-85 and rare earth ions (eg, Ce 3+ , Er 3+ , Yb 3+ ), 86 have been doped into halide perovskites. In the halide perovskite system, the similar bond energy between doped elements with X and Pb-X is considered to be one of the key factors that favors impurity incorporation.…”

Spontaneous Silver Doping and Surface Passivation of CsPbI3 Perovskite Active Layer Enable Light-Emitting Devices with an External Quantum Efficiency of 11.2%

“…11–15 Several studies also reported improvements of EQEs of CsPbBr 3 NC-based LEDs utilizing the suitable metal ion doping: namely from 0.8% to 1.4% via Mn 2+ doping; 16 from 1.0% to 4.1% via Sn 4+ doping; 17 and from 1.6% to 4.4% via Ce 3+ doping. 18 …”