Engineering Interfacial Charge Transfer in CsPbBr₃ Perovskite Nanocrystals by Heterovalent Doping

Abstract

Since compelling device efficiencies of perovskite solar cells have been achieved, investigative efforts have turned to understand other key challenges in these systems, such as engineering interfacial energy-level alignment and charge transfer (CT). However, these types of studies on perovskite thin-film devices are impeded by the morphological and compositional heterogeneity of the films and their ill-defined surfaces. Here, we use well-defined ligand-protected perovskite nanocrystals (NCs) as model systems to elucidate the role of heterovalent doping on charge-carrier dynamics and energy level alignment at the interface of perovskite NCs with molecular acceptors. More specifically, we develop an in situ doping approach for colloidal CsPbBr perovskite NCs with heterovalent Bi ions by hot injection to precisely tune their band structure and excited-state dynamics. This synthetic method allowed us to map the impact of doping on CT from the NCs to different molecular acceptors. Using time-resolved spectroscopy with broadband capability, we clearly demonstrate that CT at the interface of NCs can be tuned and promoted by metal ion doping. We found that doping increases the energy difference between states of the molecular acceptor and the donor moieties, subsequently facilitating the interfacial CT process. This work highlights the key variable components not only for promoting interfacial CT in perovskites, but also for establishing a higher degree of precision and control over the surface and the interface of perovskite molecular acceptors.

Carrier Interfacial Engineering by Bismuth Modification for Efficient and Thermoresistant Perovskite Solar Cells

“…The solution ratio information can be found in the Experimental Section. [26,27] In addition to a shift in the peak position, we also notice the increasing and shifting peaks at ≈26.6°, which indicates the higher crystallinity for the modified perovskite film. [22] The MA 3 Bi 2 Br 9 films and Bi 3+ modified perovskite films with doping concentrations (0%, 1%, 1.2%, 1.5%, 1.8%, 2%, and 5%) deposited on fluorine doped tin oxide (FTO)/cp-TiO 2 substrates were characterized by X-ray diffraction (XRD) technique, and the data are shown in Figure 1a.…”

Fully‐Inorganic Trihalide Perovskite Nanocrystals: A New Research Frontier of Optoelectronic Materials

“…[194,195] Additionally, there exist contradictory results on the energy transfer in CsPbX 3 nano-phosphors. [194,195] Additionally, there exist contradictory results on the energy transfer in CsPbX 3 nano-phosphors.…”

Postsynthetic Doping of MnCl2 Molecules into Preformed CsPbBr3 Perovskite Nanocrystals via a Halide Exchange‐Driven Cation Exchange

“…[1][2][3][4][5][6] Unlike traditional covalent bond-formed NCs, one distinguish feature of perovskite is their ionic property. [8][9][10][11][12][13][14] Instead of anion exchange, postsynthetic cation exchange is more prevalent in traditional NCs because of the wide choice of various functional cation ions endowing NCs with either peculiar optical, electron-spin, and magnetic properties or special www.advmat.de www.advancedsciencenews.com [8][9][10][11][12][13][14] Instead of anion exchange, postsynthetic cation exchange is more prevalent in traditional NCs because of the wide choice of various functional cation ions endowing NCs with either peculiar optical, electron-spin, and magnetic properties or special www.advmat.de www.advancedsciencenews.com…”