Understanding the Interplay of Binary Organic Spacer in Ruddlesden–Popper Perovskites toward Efficient and Stable Solar Cells

Abstract

Ruddlesden–Popper perovskite (RPP) materials have attracted great attention due to their superior stability, where the organic spacer dominantly determines the stability and efficiency of RPP solar cells, but research still lacks the systematical understanding of the interplay of binary spacer in the overall mixture range of 0–100% in RPPs on the precursor chemistry, film quality, and carrier behavior. Herein, a series of novel binary spacer RPP films of (PBA1−xBAx)2MA3Pb4I13 (BA = n‐butylammonium, PBA = 4‐phenylbutan‐1‐aminium, and MA = methylammonium) is successfully fabricated to reveal the interplay of binary spacers. The incorporation of 50% BA into the (PBA)2MA3Pb4I13 precursor solution increases the colloidal size and reduces nucleation sites, and therefore forms a very smooth film with much larger crystal grains and a higher degree of crystal preferential orientation, resulting in a significant reduction of trap states. The resulting combination of fast electron transfer and efficient electron extraction facilitates to effectively suppress the trap‐assisted charge recombination and remarkably decrease charge recombination losses. Consequently, the (PBA0.5BA0.5)2MA3Pb4I13 device achieves a champion efficiency of 16.0%, among the highest reported efficiencies for RPP devices. Furthermore, this device demonstrates good ambient, illumination, and thermal stabilities, retaining 60–93% of its initial efficiency after 30 days of various ageing.

Structural Disorder in Layered Hybrid Halide Perovskites: Types of Stacking Faults, Influence on Optical Properties and Their Suppression by Crystallization Engineering

“…The (A') 2/q A n−1 Pb n X 3n+1 perovskites form a homologous series with optoelectronic properties monotonically changing with the n number [5]. Owing to structural versatility and outstanding optoelectronic properties [6], LHHPs are considered perspective materials for use in perovskite solar cells [7][8][9][10], light-emitting diodes (LED) [11][12][13][14], lasers [15,16], field-effect transistors [17,18], photodetectors [19,20], etc.…”

Layer-by-Layer Structural Identification of 2D Ruddlesden–Popper Hybrid Lead Iodide Perovskites by Solid-State NMR Spectroscopy

“…Therefore, in the context of hybrid RP phases, NMR is a unique technique for determining not only the structures of the organic spacer and inorganic MHP layers but also their interaction between the spacer ligand and the inorganic metals. As many key physicochemical properties of these 2D perovskites are determined by this interlayer coupling, establishing a baseline for this layer-by-layer detection approach is crucial for characterizing the structure and dynamics of each layer in 2D perovskite phases, especially for, e.g., perovskites with mixed organic spacers that are difficult to characterize via diffraction techniques. − …”

Revealing Excitonic Phonon Coupling in (PEA)2(MA)n−1PbnI3n+1 2D Layered Perovskites

“…The excitonic and vibrational properties can be easily tailored by an appropriate choice of organic spacers from a plethora of available molecules. 9,13,17,35,[37][38][39][40][41] Despite the fact that the band-edge states of 2D perovskites are derived from metal and halide orbitals 14,[42][43][44] the absorption and emission properties are affected by the octahedral templating (steric effects), 39,42,[45][46][47] dielectric confinement 17,20 and the strength of the electron-phonon coupling. 32,35,48,49 The possibility to tune the electron-phonon coupling strength, unique for 2D perovskite semiconduc-tors, allows to tune their emissive properties from monochromatic to white-light 11,35,50 as well as controlling the carrier cooling rate 51 and transport properties 48,[52][53][54] crucial for any device.…”