Improved Crystallization Quality of FAPbBr Single Crystals by a Seeded Solution Method.

Solution-grown hybrid perovskite, FAPbBr, has attracted great attentions recently due to its inspiring optoelectronic properties and low-cost preparation method. However, challenges of solution growth for FAPbBr bulk crystals remain yet, such as uncontrollable crystalline morphologies, irregular shapes, and limited crystal sizes, which are attributed to the dense crystallization nucleus. In this work, we investigate the effects of growth conditions and seed behaviors on the crystallization quality and the yield of FAPbBr single crystals. First, the spontaneous nucleation is tailored by optimizing the precursor concentration and heating rate. Furthermore, the seeded crystals are introduced to solve the issues related to the morphology and the yield of single crystals. Based on the above-mentioned investigations, an optimized growth method, a seeded solution method, under a heating rate of 0.1 °C/h is proposed, and centimeter-scale FAPbBr single crystals with a very narrow FWHM of high-resolution X-ray diffraction rocking curves and a high yield of ∼100% of single crystals are obtained. The resulting FAPbBr single crystal exhibits a bulk resistivity of 3.42 × 10 Ω·cm and a superior / ratio over 10 under 405 nm light at a bias of 10 V. Finally, the pulse height spectra with an energy resolution of ∼21.4% are also achieved based on an AZO/FAPbBr/Au detector, illuminated using an uncollimated Am@5.49 MeV α-particle source at room temperature. This modified seeded solution method shows great potential in preparing high-quality and high-yield perovskite single crystals.