Revealing the Crystallization and Thermal-Induced Phase Evolution in Aromatic-Based Quasi-2D Perovskites Using a Robot-Based Platform

Abstract

Introducing large organic cations to form reduced-dimensional (quasi-2D) perovskites has proven to be effective in stabilizing three-dimensional perovskites. In this study, we synthesized 28 Ruddlesden–Popper-type quasi-2D perovskites using four aromatic-based cations (phenylmethylammonium (PMA), phenethylammonium (PEA), phenylpropylammonium (PPA), and phenylbutanammonium (PBA)) and systematically investigated their optoelectronic and structural properties and thermal stability. A counterintuitive finding that longer-chain PPA-based films exhibited relatively poorer stability compared to films with shorter-chain cations has been found. This instability in PPA-based samples is attributed to significant lattice distortion and a mismatched phase between face-sharing trimers, causing intense configurational strain. On the other hand, PBA-containing films maintained robust structural stability due to distinctive crystallization kinetics and a gradual phase-transformation process (from larger-n to lower-n phases) induced by a stronger steric-hindrance effect. Our study sheds light on the complex impact of aromatic-based cations on optoelectronic properties and stability of perovskites, providing guidelines for the rational compositional design engineering of highly stable perovskite materials.

Toward Self-Driven Autonomous Material and Device Acceleration Platforms (AMADAP) for Emerging Photovoltaics Technologies

“…Surprisingly, within the aromatic-based cation system, films with longer-chain phenylpropyl­ammonium cations exhibited reduced stability even compared to shorter-chain ones, primarily due to lattice distortion and phase mismatch. On the other hand, films containing phenylbutan­ammonium cations displayed robust stability, attributed to distinctive crystallization kinetics and a gradual phase transformation (from larger to smaller phases) driven by steric hindrance . We found that approximately 20–25 mol % (nominal n = 4–5) cation intercalation into MAPbI 3 can maximize the film stability, while higher or lower concentrations lead to inferior stability, which is termed stability bowing by analogy to band gap bowing .…”

“…On the other hand, films containing phenylbutanammonium cations displayed robust stability, attributed to distinctive crystallization kinetics and a gradual phase transformation (from larger to smaller phases) driven by steric hindrance. 45 We found that approximately 20−25 mol % (nominal n = 4−5) cation intercalation into MAPbI 3 can maximize the film stability, while higher or lower concentrations lead to inferior stability, which is termed stability bowing by analogy to band gap bowing. 46 These works highlighted the complex effect of the type, concentration level, and steric hindrance of intercalating cations on the perovskite stability performance.…”

Automated Synthesis of 1-Tetradecylphosphonic Acid-Capped FAPbBr3 Nanocrystals for Light Conversion in Display Applications

“…Subsequently, the NC solutions were mixed with polyacrylate resin as perovskite inks. The perovskite binder films with a diameter of 8 mm were obtained through drop-casting the inks on a glass substrate by a HT-robotic platform (Figure S6), as reported in our previous work. , To assess the photostability of the drop-casted FA/TDPA films (named FA/TDPA-DC films), all films were exposed to a blue LED at 450 nm with a homogeneous power density of 22 mW/cm 2 , as shown in Figure S7. As illustrated in Figure f, the different TDPA concentrations primarily affected the degradation in the burn-in part, which is associated with intrinsic defect traps.…”

Precise control of process parameters for >23% efficiency perovskite solar cells in ambient air using an automated device acceleration platform

“…46–48 To evaluate film homogeneity, multiple positions (13 points) with regular patterns on each sample were characterized through a high-throughput spectrometer. 49–51 The coefficient of variation (CV) of PL peak intensity extracted from these PL spectra (Fig. S16, ESI†) was calculated, as depicted in Fig.…”