Morphology Analysis and Optimization: Crucial Factor Determining the Performance of Perovskite Solar Cells

Abstract

This review presents an overall discussion on the morphology analysis and optimization for perovskite (PVSK) solar cells. Surface morphology and energy alignment have been proven to play a dominant role in determining the device performance. The effect of the key parameters such as solution condition and preparation atmosphere on the crystallization of PVSK, the characterization of surface morphology and interface distribution in the perovskite layer is discussed in detail. Furthermore, the analysis of interface energy level alignment by using X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy is presented to reveals the correlation between morphology and charge generation and collection within the perovskite layer, and its influence on the device performance. The techniques including architecture modification, solvent annealing, etc. were reviewed as an efficient approach to improve the morphology of PVSK. It is expected that further progress will be achieved with more efforts devoted to the insight of the mechanism of surface engineering in the field of PVSK solar cells.

Critical Intermediate Structure That Directs the Crystalline Texture and Surface Morphology of Organo-Lead Trihalide Perovskite

“…We further elucidate the chlorine, iodine, and lead coordination environments of the bilayer-structured octahedra in the L 1 phase with XPS. Shown in Figure a is a prominent Cl 2p core-level spectrum observed for the sample of pure L 1 phase, indicating rich Cl ions of a substantially lower binding energy (by 1.0 eV) than that of the precursor PbCl 2 reported in the literature . The result suggests full conversion of PbCl 2 into the L 1 octahedra.…”

“…Shown in Figure 2a is a prominent Cl 2p core-level spectrum observed for the sample of pure L 1 phase, indicating rich Cl ions of a substantially lower binding energy (by 1.0 eV) than that of the precursor PbCl 2 reported in the literature. 42 The result suggests full conversion of PbCl 2 into the L 1 octahedra. In practice, without complexing with the greatly out-numbered MAI, PbCl 2 of a poor solubility would have precipitated from the DMF sample solution prior to spin-coating.…”

“…10 Furthermore, the binding energy measured for the Cl ions at the octahedral terminal corners of the [PbI 4 Cl 2 ] 4− layers in L 1 (Figure 1c) is 0.7 eV lower than that for MAPbCl 3 perovskite crystals (Figure 2a) of all Cl ions taking the shared corners of [PbCl 6 ] 4− octahedra. 42,43 The relatively lower Cl binding energy is attributed to additional hydrogen bonding of the terminal Cl ions of the layered [PbI 4 Cl 2 ] 4− octahedra with the surrounding MA + moiety in the L 1 phase. It is crucial for Cl ions to take the terminal positions, as they can dissociate and escape in prolonged high-temperature annealing without disrupting the integrity of the 2D octahedral layer structure, as detailed below.…”

The Impact of Hybrid Compositional Film/Structure on Organic–Inorganic Perovskite Solar Cells

“…In the case of halogen anions, the lattice constant of ABX 3 can be increased by substituting I for Cl, thus increasing the ionic radius, and the absorption spectrum of the perovskite film will be red-shifted [ 49 ]. Perovskites with mixed X anions have been reported in the literature, with studies of the average grain size, root mean square (RMS) roughness, grain boundaries, conductivity, and other properties [ 50 ]. The addition of Br and Cl can play a regulating role.…”

Scalable Ultrasonic Spray-Processing Technique for Manufacturing Large-Area CH3NH3PbI3 Perovskite Solar Cells

“…Scaling up the size of perovskite solar cells without significant efficiency losses is a remaining challenge to be resolved. − Multimethod coaters are available to evaluate various methods during scale-up. It was also found that the morphology of the crystalline perovskite film has significant implications for manufacturing. − Large number of results regarding perovskite growth have been achieved using scalable solution deposition methods, such as blade-coating, , slot-die coating, spray-coating, − inkjet-printing, and electrodeposition . Therefore, the control of the crystal growth over a large area is a critical issue for scaling-up the perovskite absorber layer. − …”