Rational Regulation of Organic Spacer Cations for Quasi‐2D Perovskite Solar Cells

Abstract

Quasi‐two‐dimensional perovskite solar cells (quasi‐2D PSCs) have drawn significant attention and are rapidly developing owing to the impressive stability of the materials and devices. However, there are no reliable guidelines for designing and selecting suitable organic spacer cations to achieve high power conversion efficiency (PCE) in quasi‐2D PSCs. Herein, the effects of the spacer cations with different substituents, i.e., benzylamine (PMA), 4‐methoxybenzylamine (p‐MeOPMA), and 4‐fluorobenzylamine (p‐FPMA), on the optoelectronic properties and device performance of quasi‐2D perovskites are systematically investigated. It is found that the spacer cations with different substituents mainly affect the crystal growth and film quality of quasi‐2D perovskites. Interestingly, quasi‐2D perovskites based on p‐MeOPMA or p‐FPMA exhibit poor crystallinity and crystal orientation, while quasi‐2D perovskite based on the unsubstituted PMA shows improved crystallinity and crystal orientation, which enables suppressed trap densities and efficient charge transport. The PMA‐based quasi‐2D perovskite (nominal n = 3) solar cell exhibits the highest PCE of 13.58%. These results demonstrate that the rational regulation of organic spacer cations plays a crucial role in improving the crystallinity and crystal orientation of perovskite films and elucidate key guiding rules for organic spacer cations for high‐performance quasi‐2D PSCs.

Dimensional Regulation from 1D/3D to 2D/3D of Perovskite Interfaces for Stable Inverted Perovskite Solar Cells

“…30 Note that the MORI-and SMORItreated perovskite films both have weak emission peaks in the 500−600 nm region due to the PL emission of low n-value 2D perovskites. 31 To understand the effect of passivation molecules on the surface crystallinity of perovskite films, X-ray diffraction (XRD) tests were performed. As shown in Figure 1b,c, prominent diffraction peaks were observed at small angles (<10°) in the passivated perovskite film, which can be attributed to the diffraction peaks of the LD perovskite.…”

“…The significantly increased peak intensity after passivation indicates that the nonradiative recombination on the 3D perovskite surface is suppressed, which is beneficial for the device to achieve smaller open-circuit voltage loss . Note that the MORI- and SMORI-treated perovskite films both have weak emission peaks in the 500–600 nm region due to the PL emission of low n -value 2D perovskites …”

Selenophene-Based 2D Ruddlesden-Popper Perovskite Solar Cells with an Efficiency Exceeding 19%

“…6,7 Twodimensional (2D) Ruddlesden-Popper (RP) perovskites with inorganic metal halide octahedra layers sandwiched between bulky organic spacers have been developed to overcome this challenge. 8,9 This kind of structure can increase the moisture resistance of perovskite films and hinder ion migration. 10,11 However, the presence of organic spacers truncates the 3D perovskite structure, resulting in a lower dielectric constant layer surrounding the inorganic [MX 6 ] 4− sheets.…”

“…Perovskite solar cells (PSCs) have emerged as a promising next-generation photovoltaic technology. − However, the instability of perovskite materials under ambient conditions has hindered the commercialization of this technology. , Two-dimensional (2D) Ruddlesden-Popper (RP) perovskites with inorganic metal halide octahedra layers sandwiched between bulky organic spacers have been developed to overcome this challenge. , This kind of structure can increase the moisture resistance of perovskite films and hinder ion migration. , However, the presence of organic spacers truncates the 3D perovskite structure, resulting in a lower dielectric constant layer surrounding the inorganic [MX 6 ] 4– sheets. This leads to quantum and dielectric confinement, thereby increasing the exciton binding energy ( E b ) .…”

Unveiling the Impact of Organic Spacer Cations on Auger Recombination in Layered Halide Perovskites

“…Phenyl-based organic spacers are more commonly used for quasi-2D perovskite-based blue light-emitting diodes. [23][24][25] Albeit widely used, the structure-function relationships for phenylbased organic spacers are more complex and are not fully understood, specifically in relation to their optical properties such as AR. To clarify the interplay of the underlying factors that modulate the AR in these films, we examine their structural properties, excitonic binding energies, defects/film morphology and exciton-phonon coupling.…”