Formamidinium-based Ruddlesden–Popper perovskite films fabricated via two-step sequential deposition: quantum well formation, physical properties and film-based solar cells

Abstract

The use of layered perovskites is an important strategy to stabilize the formamidine (FA) based photoactive α-FAPbI3 phase. However, the growth mechanism of FA-based layered perovskites and its influence on...

Molecular Doping of Flexible Lead‐Free Perovskite‐Polymer Thick Membranes for High‐Performance X‐Ray Detection

“…The film exhibits a flat and smooth surface without any obvious grain boundaries, which is in contrast to conventional solution-cast perovskite films for solar cells, where densely packed grains are commonly observed. [24,25] We suppose that additional hot-pressing after thermal annealing during PFM fabrication leads to recrystallization or ripening, which accounts for the elimination of grain boundaries. The cross-sectional SEM image shows good fusion of MA 3 Bi 2 I 9 with a flexible nylon membrane, which helps form an efficient charge transport pathway within the membrane.…”

Molecular Doping of Flexible Lead‐Free Perovskite‐Polymer Thick Membranes for High‐Performance X‐Ray Detection

“…Figure 1d presents planar and cross‐sectional scanning electron microscopy (SEM) images of the MA 3 Bi 2 I 9 PFM. The film exhibits a flat and smooth surface without any obvious grain boundaries, which is in contrast to conventional solution‐cast perovskite films for solar cells, where densely packed grains are commonly observed [24, 25] . We suppose that additional hot‐pressing after thermal annealing during PFM fabrication leads to recrystallization or ripening, which accounts for the elimination of grain boundaries.…”

Molecularly Functionalized SnO2 Films by Carboxylic Acids for High-Performance Perovskite Solar Cells

“…The charge transport properties of different ETLs were then analyzed through the space charge limit current (SCLC) method. Figure 1c presents the fitted J−V curves of the electron-only devices (ITO/Al/ETL/Al), and the electron mobility (μ e ) was extracted using the Mott−Gurney Law: 32 JL V…”

“…The charge transport properties of different ETLs were then analyzed through the space charge limit current (SCLC) method. Figure c presents the fitted J – V curves of the electron-only devices (ITO/Al/ETL/Al), and the electron mobility (μ e ) was extracted using the Mott–Gurney Law: μ e = 8 J L 3 9 ε 0 ε normalr V 2 where J is the current density, L is the thickness of ETL, V is the applied voltage, ε 0 is the vacuum permittivity, and ε r is the relative dielectric constant. Upon modification with the carboxylic acid molecules, the calculated electron mobility is increased from the 1.7 × 10 –3 cm 2 V –1 s –1 of pristine SnO 2 to the 2.4 × 10 –3 and 3.6 × 10 –3 cm 2 V –1 s –1 of PA-SnO 2 and CA-SnO 2 , benefiting the enhanced charge transport at the acid-modified electron extraction interface.…”

“…The dark current shows a sharply nonlinear rise after passing the V TFL bending point, which can thus be extracted from the fitted curves in this SCLC region. The trap density ( n trap ) can then be calculated by the following equation 0.25em n trap = 2 ε 0 ε normalr V TFL normale L 2 where e is the elementary charge and L is the thickness of the perovskite layer. With acid modification, the V TFL values were determined to decrease from the 0.30 of the SnO 2 film to the 0.24 and 0.16 V of the PA-SnO 2 - and CA-SnO 2 -based perovskite films, respectively, illustrating the remarkable reduction in trap density from 3.7 × 10 15 to 2.9 × 10 15 and 2.0 × 10 15 cm –3 .…”