How the ionic liquid BMIMBF₄ influences the formation and optoelectronic properties of MAPbI₃ thin films

Abstract

While using additives such as ionic liquids (IL) is known to boost the efficiency and stability of perovskite solar cells, it is still unclear how ILs impact the difficile perovskite...

Performance Enhancement of Quasi-Two-Dimensional Perovskite Light-Emitting Diodes by Constructing an Efficient Energy Funnel via Ionic Liquid Doping

“…The role of the BF 4 – anion has not been clarified, although the positive effect has been demonstrated by comparing with other halide dopants similar to the BMIMBr. Further study indicates that the BMIMBF 4 could slow down the crystallization process of the perovskite phase, which is proved by in situ optical spectroscopy …”

“…Further study indicates that the BMIMBF 4 could slow down the crystallization process of the perovskite phase, which is proved by in situ optical spectroscopy. 36 Through our comparison of physical properties between BMIMBr and BMIMBF 4 doping, we can find that the BF 4 − anion shows a strong influence on the crystallization process in the quasi-2D crystallization process (Figure 7). The PL spectra of the samples indicate that the phase distributions of the films are very dependent on the types of anions (Br − or BF 4 − ).…”

To Stop or to Shuttle Halides? The Role of an Ionic Liquid in Thermal Halide Mixing of Hybrid Perovskites

“…However, with increasing temperature, narrow 1 H signals corresponding to the imidazolium cation of the IL (BMIM + ) emerge (Figures 4A and S10). 59 At room temperature and up to 55 °C, the 1 H MAS NMR signals are broad, as BMIM + coordinates to the perovskite surface resulting in a solid character 36 and passivates defect and trap states there. 43 The temperature-dependent narrowing of the BMIM + signals is due to a high increase in BMIM + mobility resulting in a liquid-like state (averaging of 1 H dipolar coupling terms) of the additive cations at high temperature.…”

First of Their Kind: Solar Cells with a Dry‐Processed Perovskite Absorber Layer via Powder Aerosol Deposition and Hot‐Pressing

“…One inherent limitation of solution‐based and evaporation methods is the intrinsic coupling between perovskite synthesis and film formation, rendering the morphology and final optoelectronic functionality of perovskite films to be extremely sensitive to the precise processing conditions. [ 7–10 ] Moreover, a second drawback of solution‐based processing is the need for toxic solvents such as dimethylfluorene (DMF) [ 11,12 ] to prepare the precursor stock solutions. Replacing these toxic solvents was already subject of several studies with the aim to find greener alternatives for perovskite stock solutions.…”

“…One inherent limitation of solutionbased and evaporation methods is the intrinsic coupling between perovskite synthesis and film formation, rendering the morphology and final optoelectronic functionality of perovskite films to be extremely sensitive to the precise processing conditions. [7][8][9][10] Moreover, a second drawback of solution-based processing is the need for toxic solvents such as dimethylfluorene (DMF) [11,12] to prepare the precursor Preparing halide perovskite films by solvent-free, powder-based processing approaches currently attracts more and more attention. However, working solar cells employing dry, powder-based halide perovskite thin films, have not been demonstrated so far.…”