Hydroxyl Functional Groups in Two-Dimensional Dion–Jacobson Perovskite Solar Cells

Abstract

In this work we demonstrate a new diammonium spacer molecule with hydroxyl functional groups forming a Dion−Jacobson perovskite. Polarization modulation infrared reflection absorption spectroscopy reveal hydrogen bonding between the iodide to the spacer molecule and in between the OH groups. As a result, we were able to demonstrate n = 5 low dimensional perovskite solar cell (LDPSC) with an efficiency of 10%. Photoconductivity measurements and scanning tunneling spectroscopy draw the band structure of this low dimensional perovskite (LDP) revealing in-gap states adjacent to the conduction band edge, consistent with Shockley−Reed−Hall modeling of the temperature-dependent photoconductivity. The LDPSC based on the diammonium spacer H 3 N−C 4 H 6 (OH) 2 −NH 3 shows enhanced stability under a relative humidity of more than 50% over 1030 h. Evaluating the mechanism of the cell shows a misalignment of the hole selective contact with the LDP. Improving this interface can increase further the photovoltaic performance, demonstrating the potential of this new type of diammonium spacer in LDP.

Vapor Deposited Pure α‐FAPbI3 Perovskite Solar Cell via Moisture‐Induced Phase Transition Strategy

“…Formation of H 2 O … HN hydrogen bond between H 2 O and FA + cation has been suggested. [ 15 ] To form the H 2 O … HN hydrogen bond, the distances of H … O should be less than the sum of the van der Waals radii of 2.60 Å. [ 16 ] The distances between the O atom in H 2 O and H atom in adjacent FA + given in Figure S12 (Supporting Information) are in the range of 1.7 to 2.0 Å, which confirms the formation of hydrogen bond.…”

“…Previously, moisture‐induced phase transition of FAPbI 3 is suggested to be similar to that of CsPbI 3 , [ 19 ] whose phase transition is triggered by the H 2 O induced I − vacancy; or considered as a result of strain in (111) plane. [ 15c,20 ] From the above picture, the moisture‐induced phase transition of FAPbI 3 is not the same as the vacancy‐induced mechanism in CsPbI 3 , and the observed strain in (111) is the result of volume contraction due to the hydrogen bonding. The gradual change in volume at low x means that the lattice of α‐FAPbI 3 kept relatively stable under a low concentration of water (Low RH).…”

Metal Halide Perovskite Alloy: Fundamental, Optoelectronic Properties and Applications

“…[ 97 ] Cohen and co‐worker reported a new 2D perovskite of (H 3 H‐C 4 H 6 (OH) [ 2 ] − NH 3 )(Cs 0.2 MA 0.13 FA 0.67 ) 4 Pb 5 (I 0.9 Br 0.1 ) 16 , and the diammonium spacer H 3 H‐C 4 H 6 (OH) 2 ‐NH 3 with the hydroxyl functional groups provides intermolecular hydrogen bonds, which can increase the interactions between the PbI 4 2− framework and further enhance the stability of this 2D perovskite. [ 98 ] However, the photoelectric property of alloyed 2D perovskite is poor due to larger bandgap. Therefore, the alloyed 2D/3D perovskites were proposed.…”

Stabile fluoro-benzene-based spacer for lead-free Dion–Jacobson perovskites

“…7 Therefore, the DJ OIHPs without the van der Waals gap might be suitable for optoelectronic device applications, and there has been much research discussion on the DJ OIHPs. [10][11][12][13][14][15][16] The DJ OIHPs have opened a new extension research eld with better stability and optoelectronic properties for the two-dimensional lead perovskites and are more complicated than the typical perovskite with the ABX 3 structure. The divalent ammonium spacer cations have different aromatic rings and functional groups between the two ammonium cations on the head and tail.…”