Single‐Crystal Seeds Inducing the Crystallization of High‐Performance α‐FAPbI₃ for Efficient Perovskite Solar Cells

Abstract

𝜶-phase formamidine lead iodine (𝜶-FAPbI 3 ) as a competitive candidate to pursue high-performance perovskite solar cells (PSCs) suffers from the weakness of random nucleation and disordered growth in chasing high-grade polycrystalline films. Here, single-crystal seeds crystallization (SCSC) method is proposed to obtain high-quality 𝜶-FAPbI 3 perovskite films for the first time. Six single-crystals seeds (CsPbBr 3 , CsPbI 3 , FAPbBr 3 , FAPbI 3 , MAPbBr 3 , and MAPbI 3 ) are employed to regulate 𝜶-FAPbI 3 perovskite crystallization. These seeds act as nucleation sites and allow the perovskite to grow directly. The rapid crystallization significantly improves the crystallinity of perovskite films with uniform morphology, large grain size, and less defects. Of particular note, FAPbBr 3 seed prefers to grow 𝜶-FAPbI 3 epitaxially from FAPbBr 3 @PbI 2 heterostructure through a halogen anion exchange process. The average grain size of FAPbBr 3-perovskite film is boosted to 2.6 μm, and the trap density reduced by 11 times. The resultant FAPbBr 3 -PSCs achieve a maximum power conversion efficiency (PCE) of 23.84% with a high open-circuit voltage of 1.18 V. The unencapsulated PSC retains 91% of the initial PCE after 3000 h of storage at ≈30-50% relative humidity and preserves 98.5% of the original value after 155 h illumination with maximum power point tracking.

Accelerating Thermal Transfer in Perovskite Films for High‐Efficiency and Stable Photovoltaics

“…As shown in Figure a and Figure S25 (Supporting Information), the shelf‐storage lifetime of MWCNTs‐doped PSC is prolonged, with a smaller PCE attenuation rate of 6% compared to that of 25% for reference sample after 2880 h under air condition without encapsulation, delivering an extended T 80 lifetime of 9600 h. Because the storage temperature ( T ) and relative humidity (RH) are controlled at 25 °C and 10%, respectively, we mainly attribute the improved stability to the better perovskite crystallinity (less defects), which can significantly mitigate moisture penetration and restrain the detrimental phase decomposition. [ 64,65 ] Different from the mild stimulus, we further conducted the SPO tracking of encapsulated devices under persistent irradiation without UV filtering treatment (AM 1.5G, 100 mW cm −2 ; T = 25 °C, RH = 30%), and the PCE evolution over time is shown in Figure 5b. For the control device, the PCE decreases to nearly zero after light irradiation for 100 h; by contrast, the target device still remains at 80% of initial efficiency after illumination for 250 h. As a result, a remarkable photostability improvement of 40‐fold is achieved.…”

Templated-seeding renders tailored crystallization in perovskite photovoltaics: path towards future efficient modules

“…The precursor solution, essential for perovskite film preparation, can be enhanced by the effective seed-assisted growth method, which involves introducing seeds into the solution to improve film quality and device performance. Various seed materials to date, including perovskite-based seeds, 46,47 nanocrystals, and additives, 48 have been utilized to promote nucleation and enhance crystal growth, leading to improved performance and stability of perovskite solar cells.…”

Unveiling Electron Dose-Induced Phase Decomposition and Energy Kinetics in Cu-Doped CsPbI3 Nanocrystals

“…The remarkable luminescent properties of lead halide perovskites (LHPs), coupled with efficient charge transport, high light absorption coefficient, tunable optical emission, and affordable synthesis costs, have catapulted them to the forefront of scientific research. − They are generally found in the form ABX 3 with large monovalent cations (MA + , FA + , Cs + ) and smaller divalent metal cations (Pb 2+ , Sn 2+ , etc.) occupying the A and B sites, respectively, while halide ions (Cl – , Br – , I – ) , cover the X sites.…”