Solid-phase hetero epitaxial growth of α-phase formamidinium perovskite

Abstract

Conventional epitaxy of semiconductor films requires a compatible single crystalline substrate and precisely controlled growth conditions, which limit the price competitiveness and versatility of the process. We demonstrate substrate-tolerant nano-heteroepitaxy (NHE) of high-quality formamidinium-lead-tri-iodide (FAPbI3) perovskite films. The layered perovskite templates the solid-state phase conversion of FAPbI3 from its hexagonal non-perovskite phase to the cubic perovskite polymorph, where the growth kinetics are controlled by a synergistic effect between strain and entropy. The slow heteroepitaxial crystal growth enlarged the perovskite crystals by 10-fold with a reduced defect density and strong preferred orientation. This NHE is readily applicable to various substrates used for devices. The proof-of-concept solar cell and light-emitting diode devices based on the NHE-FAPbI3 showed efficiencies and stabilities superior to those of devices fabricated without NHE.

Performance-limiting formation dynamics in mixed-halide perovskites

“…This indicates that a halide homogenization process must have occurred during the growth stage to achieve the target stoichiometry from the initial Br-rich phase. Such a homogenization process occurs by diffusion of iodide to incorporate into the initial Br-rich phase, which introduces an activation energy barrier and is consistent with a retardation of the perovskite growth ( 19 ). We further explored the FACs (MA-free) composition, which has also been reported to be highly resistant to halide segregation and delivers high PCE.…”

Defect mitigation using d-penicillamine for efficient methylammonium-free perovskite solar cells with high operational stability

“… 4 Alternatively, a formamidinium (FA) based perovskite was employed to counter these issues due to its improved thermal stability (up to 150 °C) along with its favorable optical bandgap (1.48 eV) for absorbing solar irradiation. 5 However, other ions, such as MA + , 1 d Cs + (Rb + ), 4 as well as low-dimensional perovskites, 6 are still required to stabilize the photoactive black α-FAPbI 3 . 7 The development of MA-free (where it refers to not only the resultant perovskite film, but also the precursor solution), Cs/FA perovskites is potentially an effective strategy to address the intrinsic thermal instability related to perovskite materials.…”

Dynamic structural property of organic-inorganic metal halide perovskite

“…The halide materials show great promise for decreasing the grid parity taking advantages of low-cost starting materials ( Kim et al., 2012 , 2020 ; Lee et al., 2019 ; Seo et al., 2019 ), high throughput ( Brenner et al., 2016 ), and low-temperature fabrication techniques compared with the traditional monocrystalline Si and III-V PV devices ( Brenner et al., 2016 ; Ding et al., 2020a ; Kim et al., 2017 ; Lee et al., 2019 ; Seo et al., 2019 ). Not only the PV devices but also the superior optoelectronic properties of the halide perovskites enable application of the materials in a variety of devices including photodetectors ( Chun et al., 2018 ; Saidaminov et al., 2015 ), light emitting diodes( Lee et al., 2017 , 2020 ), transistors ( Senanayak et al., 2017 ), memories ( Kim et al., 2019 ; Yang et al., 2018 ), nanogenerators ( Ding et al., 2020b ), and spintronics ( Wang et al., 2019 ).…”