Pressure-Engineered Optical and Charge Transport Properties of Mn²⁺/Cu²⁺ Codoped CsPbCl₃ Perovskite Nanocrystals via Structural Progression

Abstract

In this work, compared with the corresponding pure CsPbCl3 nanocrystals (NCs) and Mn2+-doped CsPbCl3 NCs, Mn2+/Cu2+-codoped CsPbCl3 NCs exhibited improved photoluminescence (PL) and photoluminescence quantum yields (PL QYs) (57.6%), prolonged PL lifetimes (1.78 ms), and enhanced thermal endurance (523 K) as a result of efficient Mn2+ doping (3.66%) induced by the addition of CuCl2. Furthermore, we applied pressure on Mn2+/Cu2+-codoped CsPbCl3 NCs to reveal that a red shift of photoluminescence followed by a blue shift was caused by band gap evolution and related to the structural phase transition from cubic to orthorhombic. Moreover, we also found that under the preheating condition of 523 K, such phase transition exhibited obvious morphological invariance, accompanied by significantly enhanced conductivity. The pressure applied to the products treated with high temperature enlarged the electrical difference and easily intensified the interface by closer packaging. Interestingly, defect-triggered mixed ionic and electronic conducting (MIEC) was observed in annealed NCs when the applied pressure was 2.9 GPa. The pressure-dependent ionic conduction was closely related to local nanocrystal amorphization and increased deviatoric stress, as clearly described by in situ impedance spectra. Finally, retrieved products exhibited better conductivity (improved by 5–6 times) and enhanced photoelectric response than those when pressure was not applied. Our findings not only reveal the pressure-tuned optical and electrical properties via structural progression but also open up the promising exploration of more amorphous all-inorganic CsPbX3-based photoelectric applications.

Defect Passivation of Mn2+-Doped CsPbCl3 Perovskite Nanocrystals as Probed by Scanning Tunneling Spectroscopy: Toward Boosting Emission Efficiencies

“…Similarly, the introduction of Cu 2+ ions resulted in an identical shift of the corresponding diffraction peak to a larger angle, inferring simultaneous dual doping of Cu 2+ −Mn 2+ into the host lattice. 11,31 In addition to a shift in XRD peaks, broadening of the peaks was also noticed, inferring a lattice strain as well due to doping. To further confirm the codoping, we recorded XPS spectra of Cu 2+ −Mn 2+ -codoped CsPbCl 3 NCs (2/1/1) as a representative sample.…”

“…Two strong diffraction peaks at about 15.8 and 31.9°representing the (100) and (200) planes were observed in CsPbCl 3 NCs, inferring a cubic crystal structure in all the members. 11,17,24,31 Upon Cu 2+ −Mn 2+ codoping, no new diffraction peaks appeared, indicating the retention of the parent cubic structure. In this direction, we compared a higher intense (200) diffraction peak for CsPbCl 3 and Mn 2+ -doped and Cu 2+ −Mn 2+ -codoped perovskites as well (Figure 2b).…”

“…In the description of the results in later sections, we referred to the feed ratio for simplicity and to be consistent with existing reports. 11,17,24,30,31 3.2. Steady-State PL of Perovskite NCs.…”

Recent Advances in Enhancing and Enriching the Optical Properties of Cl‐Based CsPbX3 Nanocrystals

“…applied pressure on Mn 2+ /Cu 2+ codoped CsPbCl 3 NCs to reveal that a red shift of photoluminescence followed by a blue shift was caused by bandgap evolution and is related to the structural phase transition from cubic to orthorhombic. [ 108 ] Additionally, Ding et al. reported that Cr 3+ , Yb 3+ , Ce 3+ tri‐doped CsPbCl 3 display an ultrahigh PLQY of 188% and excellent stability.…”

“…Zhang et al applied pressure on Mn 2+ / Cu 2+ codoped CsPbCl 3 NCs to reveal that a red shift of photoluminescence followed by a blue shift was caused by bandgap evolution and is related to the structural phase transition from cubic to orthorhombic. [108] Additionally, Ding et al reported that Cr 3+ , Yb 3+ , Ce 3+ tri-doped CsPbCl 3 display an ultrahigh PLQY of 188% and excellent stability. They suggested that Cr 3+ doping enhanced the exciton binding energy, reduced defects, improved the tolerance factor and the energy transfer rates from NCs to Yb 3+ by bridging the energy gap by Ce 3+ ion doping.…”