Doping Strategies for Promising Organic–Inorganic Halide Perovskites

Abstract

up, but their weaknesses (bad stability and low efficiency) are obvious although it is expected as a promising candidate to address the toxicity of lead. [33] There are at least four main issues to be solved: i) The poor stability due to the oxidation of Sn 2+ in a low water and oxygen environment.ii) The low formation energy of Sn vacancies. iii) The fast formation rate of perovskite leads to poor film formation quality. iv) The mismatch of energy levels between SOIHP layer and the charge transport layer results in the charge transport barrier. [34] Therefore, it is urgent to resolve these problems in the POIHPs and SOIHPs to improve their performance, promoting the commercial application of perovskites in many fields. In order to address the issues aforementioned, compositional engineering plays a key role in achieving highly efficient and stable OIHPs. Notably, the modification of properties through ion doping is an effective way to improve the performance and broaden the application field of OIHPs in recent years, [1,[35][36][37][38][39][40] involving solar cells, light-emitting diodes, transistors, and so on. [1,4,6,41] In order to better understand doping, it is important to study the structural characteristics of perovskites. There are two main kinds of perovskites 3D and 2D perovskites, which were extensively explored in recent years. The typical 3D structure can be expressed as ABX 3 , where A is an organic cation such as CH 3 NH 3 + (MA), (NH 2 ) 2 CH + (FA), and Cs + ; B is a divalent cation such as Pb 2+ and Sn 2+ (we only mentioned in this article); X is halogen anions such as Cl − , Br − , and I − , respectively. The 2D perovskites can be categorized as Ruddlesden-Popper phase (RPP) A' 2 A n-1 B n X 3n+1 with 1 ≤ n < ∞, Dion-Jacobson phase (DJP) A''A n-1 B n X 3n+1 with 1 ≤ n < ∞, and alternating cations in the interlayer phase (ACIP) A'''A n B n X 3n+1 , where the A', A'' and A''' are an organic spacer cation such as aromatic or aliphatic alkylammonium monovalent cations; diamine compounds with two amino groups forming hydrogen bonds on both ends with the inorganic "quantum wells" (bivalent cations), and guanidine (GA), respectively. [1,[42][43][44] There are also lower-dimension (LD) perovskites such as 1D and 0D. [45][46][47] The ions doping can occur at the A, B, and X sites, or simultaneously happen at these sites. The doping that we mentioned in perovskite may differ from other semiconductors where it refers to a very small concentration of element addition, while our "doping" refers to a large amount of element addition which is more like an alloy or so. With the different doping strategies, the properties of POIHP and SOIHP can be effectively controlled or modified. The relationship between the

Macroscopic Piezoelectricity of Halide Perovskite Single Crystals and Their Highly Sensitive Self-Powered X-ray Detectors

“…With the doping concentration x increasing, the diffraction peaks at 2θ ∼ 28.5° shift toward lower angles (Figure b). The derived expansion of the lattice structure comes from the substitution of smaller MA + ions ( r = 0.270 nm) with larger FA + ions ( r = 0.279 nm) . The refined XRD patterns and specific crystal parameters for FA x SCs ( x = 0–0.15) are shown in Figure S2b–f and Table S1.…”

“…The derived expansion of the lattice structure comes from the substitution of smaller MA + ions (r = 0.270 nm) with larger FA + ions (r = 0.279 nm). 11 The refined XRD patterns and specific crystal parameters for FA x SCs (x = 0−0.15) are shown in Figure S2b−f and Table S1. According to the refinement results, the FA x SCs change from the tetragonal phase (x = 0−0.1, a = b < c) to the cubic phase (x = 0.125−0.15, a = b = c) at room temperature (Figure 1c).…”

A DFT study on CH3NH3MnBr3: a novel multiferroic organic–inorganic hybrid perovskite

“…23,24 The exceptional optoelectronic and electromechanical properties of organic-inorganic hybrid perovskites (OIHPs) can be attributed to their highly tunable composition, structure, and dimensionality. [25][26][27] Notably, the presence of ferroelectricity in OIHPs, arising from the alignment of polar cations, plays a crucial role in effectively separating photogenerated electronhole pairs and reducing charge recombination. [28][29][30][31][32][33] Stroppa et al utilized a blend of DFT calculations and symmetry mode analysis to investigate the ferroelectric polarization of MAPbI 3 .…”

Unlocking the potential of metal halide perovskite thermoelectrics through electrical doping: A critical review

“…However, the low electrical conductivity, and therefore a low power factor, of MHPs has been one of the main limiting factors for realizing high thermoelectric figure of merit ( ZT ), unlike numerous theoretical results previously reported in the field, 33–36 mainly due to the absence of effective doping methods for controlling their carrier concentration (see Figure 1A,C). Previous doping studies in MHPs have mainly focused on improving their optical properties or film quality and stability, whereas tackling the inherent electrical doping issues in MHPs has not been particularly emphasized 37–40 …”

“…Previous doping studies in MHPs have mainly focused on improving their optical properties or film quality and stability, whereas tackling the inherent electrical doping issues in MHPs has not been particularly emphasized. [37][38][39][40] In this critical review, we attempt to address the importance of developing effective doping strategies for MHP thermoelectrics and the resulting impact on charge transport mechanisms. While previous reviews have mainly focused on the general thermoelectric 41,42 and thermal transport properties 43,44 of MHPs, a gap remains in directly addressing electrical doping strategies [45][46][47][48] for MHP thermoelectrics and their resulting impact on charge transport.…”