Advancements in Perovskite Nanocrystal Stability Enhancement: A Comprehensive Review

Abstract

Over the past decade, perovskite technology has been increasingly applied in solar cells, nanocrystals, and light-emitting diodes (LEDs). Perovskite nanocrystals (PNCs) have attracted significant interest in the field of optoelectronics owing to their exceptional optoelectronic properties. Compared with other common nanocrystal materials, perovskite nanomaterials have many advantages, such as high absorption coefficients and tunable bandgaps. Owing to their rapid development in efficiency and huge potential, perovskite materials are considered the future of photovoltaics. Among different types of PNCs, CsPbBr₃ perovskites exhibit several advantages. CsPbBr₃ nanocrystals offer a combination of enhanced stability, high photoluminescence quantum yield, narrow emission bandwidth, tunable bandgap, and ease of synthesis, which distinguish them from other PNCs, and make them suitable for various applications in optoelectronics and photonics. However, PNCs also have some shortcomings: they are highly susceptible to degradation caused by environmental factors, such as moisture, oxygen, and light, which limits their long-term performance and hinders their practical applications. Recently, researchers have focused on improving the stability of PNCs, starting with the synthesis of nanocrystals and optimizing (i) the external encapsulation of crystals, (ii) ligands used for the separation and purification of nanocrystals, and (iii) initial synthesis methods or material doping. In this review, we discuss in detail the factors leading to instability in PNCs, introduce stability enhancement methods for mainly inorganic PNCs mentioned above, and provide a summary of these approaches.

Keywords: enhancement; perovskite nanocrystals; stability.

Figure 1

(a) Chart of highest confirmed conversion efficiencies for a range of photovoltaic technologies across decades. (b) Crystal structure of perovskite. (c) Schematic diagram of perovskite phase.

Figure 2

(a) Representative transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) images of CsPbBr₃ PNCs. (b) Representative TEM and HRTEM images of CsPbI₃ PNCs. (c) Representative confocal laser scanning microscopy (CLSM) (left) and SEM (right) images of polylactic acid (PLA) chambers loaded with CsPbBr₃ PNCs (inner). (d) Representative CLSM (left) and SEM (right) images of PLA chambers loaded with CsPbI₃ PNCs (inner). (e) Representative CLSM images of PLA chambers loaded with CsPbBr₃/CsPbI₃ (inner/outer) PNCs. (f) Representative CLSM (left) and SEM (right) images of PLA micro-sized carriers loaded with CsPbBr₃ PNCs. (g) Representative CLSM (left) and SEM (right) images of PLA micro-sized carriers loaded with CsPbI₃ PNCs. (h) Relative photoluminescence (PL) intensity of CsPbBr₃ PNCs loaded in PLA/PMMA/PCL chambers (inner, outer, and both) incubated in water, PBS, and HS for varying durations (0, 1, 4, or 7 days). Reproduced from [89] with permission of the American Chemical Society. (i) In situ synthesis of carbon nitride protected CsPbBr₃ (CNMBr) using CsPbBr₃ and monolayered graphenic carbon nitride (CNM). Reproduced from [91] with permission of Elsevier.

Figure 2

(a) Representative transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) images of CsPbBr₃ PNCs. (b) Representative TEM and HRTEM images of CsPbI₃ PNCs. (c) Representative confocal laser scanning microscopy (CLSM) (left) and SEM (right) images of polylactic acid (PLA) chambers loaded with CsPbBr₃ PNCs (inner). (d) Representative CLSM (left) and SEM (right) images of PLA chambers loaded with CsPbI₃ PNCs (inner). (e) Representative CLSM images of PLA chambers loaded with CsPbBr₃/CsPbI₃ (inner/outer) PNCs. (f) Representative CLSM (left) and SEM (right) images of PLA micro-sized carriers loaded with CsPbBr₃ PNCs. (g) Representative CLSM (left) and SEM (right) images of PLA micro-sized carriers loaded with CsPbI₃ PNCs. (h) Relative photoluminescence (PL) intensity of CsPbBr₃ PNCs loaded in PLA/PMMA/PCL chambers (inner, outer, and both) incubated in water, PBS, and HS for varying durations (0, 1, 4, or 7 days). Reproduced from [89] with permission of the American Chemical Society. (i) In situ synthesis of carbon nitride protected CsPbBr₃ (CNMBr) using CsPbBr₃ and monolayered graphenic carbon nitride (CNM). Reproduced from [91] with permission of Elsevier.

Figure 3

(a) Schematic diagrams of the interaction between the CsPbBr₃ nanocrystals and the DTDB ligand, and the chemical structure of the DTDB and DTAB ligands. Reproduced from [118] with permission of the Royal Society of Chemistry. (b) Ligand content (wt.%) at the surface of OLA- and AHDA-PNCs determined from TGA curves after several purification cycles. Reproduced from [121] with permission of the American Chemical Society. (c) Schematic representation of the effect of CA ligand enhancement and recovery of PL intensity and stability by multifunctional etching ligand treatment for PNCs. Reproduced from [122] with permission of Elsevier.

Figure 4

(a) Urbach energy plot of pristine and Cr-doped PNCs. Reproduced from [138] with permission of the Royal Society of Chemistry. (b) Schematic diagram showing a possible reaction that occurs when three additional elements are doped in the perovskite lattice upon mixing with a metal halide powder blend. (c) Representative photographs of synthesized colloidal solutions under UV excitation. Each sample is labeled with the B site elements, e.g., PbZnCd for MA(PbZnCd)Br₃ HEP nanocrystals. Reproduced from [140] with permission of the American Chemical Society.

Figure 5

(a) Schematic representation of surface treatment of CsPbX₃ PNCs with ascorbic acid. Reproduced from [161] with permission of the American Chemical Society. (b) Schematic illustration of the perovskite metal–organic framework (PeMOF) fabrication process. Reproduced from [163] with permission of Wiley. (c) Synthesis schematic core–shell structured CsPbBr₃–polymer nanoparticles. Reproduced from [164] with permission of the American Chemical Society.