| Affiliation: | 1. School of Chemistry, Beijing Advanced Innovation Center, for Biomedical Engineering, Beihang University, No. 37 Xueyuan Road, Beijing, 100191 P.R. China CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience National Center, for Nanoscience and Technology, Beijing, 100190 P.R. China;2. School of Chemistry, Beijing Advanced Innovation Center, for Biomedical Engineering, Beihang University, No. 37 Xueyuan Road, Beijing, 100191 P.R. China;3. CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience National Center, for Nanoscience and Technology, Beijing, 100190 P.R. China;4. Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands |
| Abstract: | A comprehensive study unveiling the impact of heterovalent doping with Bi3+ on the structural, semiconductive, and photoluminescent properties of a single crystal of lead halide perovskites (CH3NH3PbBr3) is presented. As indicated by single-crystal XRD, a perfect cubic structure in Bi3+-doped CH3NH3PbBr3 crystals is maintained in association with a slight lattice contraction. Time-resolved and power-dependent photoluminescence (PL) spectroscopy illustrates a progressively quenched PL of visible emission, alongside the appearance of a new PL signal in the near-infrared (NIR) regime, which is likely to be due to energy transfer to the Bi sites. These optical characteristics indicate the role of Bi3+ dopants as nonradiative recombination centers, which explains the observed transition from bimolecular recombination in pristine CH3NH3PbBr3 to a dominant trap-assisted monomolecular recombination with Bi3+ doping. Electrically, it is found that the mobility in pristine perovskite crystals can be boosted with a low Bi3+ concentration, which may be related to a trap-filling mechanism. Aided by temperature (T)-dependent measurements, two temperature regimes are observed in association with different activation energies (Ea) for electrical conductivity. The reduction of Ea at lower T may be ascribed to suppression of ionic conduction induced by doping. The modified electrical properties and NIR emission with the control of Bi3+ concentration shed light on the opportunity to apply heterovalent doping of perovskite single crystals for NIR optoelectronic applications. |
