High Performance of Planar Perovskite Solar Cells Produced from PbI₂(DMSO) and PbI₂(NMP) Complexes by Intramolecular Exchange

Abstract

intermediate phase is another very effective way to transfer a uniform and high-quality perovskite fi lm because the intermediate phase can slow down the reaction between PbI 2 and FAI in solution. [ 27 ] Recently, intramolecular exchange has been shown to dramatically improve the power conversion effi ciency of perovskite solar cells (PSCs), and such exchange of DMSO intercalated in PbI 2 (PbI 2 (DMSO) complex) with FAI leads to crystallization of FAPbI 3 because FAI has a higher affi nity for PbI 2 than does DMSO. [ 9 ] This exchange neither increased the volume nor changed the thickness of the as-coated PbI 2 (DMSO) fi lm because the molecular sizes of FAI and DMSO are similar, and hence a stable, dense, and uniform perovskite fi lm was fabricated.The intercalation of layered PbI 2 with different organic molecules has been studied a useful method to fabricate inorganic-organic compounds with novel properties. [ 28 ] The structure of PbI 2 consists in sandwich-type layers, which contains a plane of Pb ions sandwich-type between two planes of hexagonally arranged I ions. The ionic bonds within I-Pb-I layers are strong while those between adjacent sandwiched layers are weak. [ 29 ] Therefore, the van der Waals interactions between interlayer bonding allows a successfully insertion of different guest molecules. [ 30,31 ] As mentioned above, the PbI 2 (DMSO) complex (DMSO intercalated in layered PbI 2 ) can be successfully converted into perovskite with intramolecular exchange. In this paper, we report that the N -Methyl-2 -pyrrolidone (NMP) molecule also can be intercalated into layered PbI 2 and the PbI 2 (NMP) complex successfully converted into high-quality perovskite with intramolecular exchange. Compared to perovskite fi lms derived from the PbI 2 (DMSO) complex, those derived from the PbI 2 (NMP) complex were found to display a higherquality perovskite layer morphology and higher power conversion effi ciency. While planar perovskite solar cells derived from PbI 2 (DMSO) complex achieved a 15.8% average and 17.1% maximum power conversion effi ciency, those derived from the PbI 2 (NMP) complex achieved a 17.6% average and 19.5% maximum power conversion effi ciency.A previous study has shown that the PbI 2 (DMSO) fi lm has typically been obtained in various steps: [ 9 ] fi rst by synthesizing the PbI 2 (DMSO) 2 complex from a mixture of PbI 2 and DMSO and adding a nonpolar solvent such as toluene; then producing PbI 2 (DMSO) complex from the PbI 2 (DMSO) 2 complex by applying a vacuum oven treatment for 24 h; and fi nally dissolving PbI 2 (DMSO) complexes in DMF and spin-coating this solution on the substrate. Interestingly, we found that the PbI 2 (DMSO) or PbI 2 (NMP) fi lms could be deposited using Of the many materials and manufacturing techniques aimed at fabricating highly effi cient and low-cost photovoltaic cells, hybrid organic-inorganic solar cells that utilize perovskitebased materials as the light-harvesting component have been of great interest as an exciting alternative to third-generation photovo...

Capturing the Sun: A Review of the Challenges and Perspectives of Perovskite Solar Cells

“…[35] Thus, complex-forming solvents can be used to "pre-stretch" the PbI 2 lattice for the organic compounds that are incorporated into the structure via a molecule exchange reaction. [36] An example of this is depicted for DMSO and NMP in Figure 2b.…”

“…[36,38,39] So-called polar aprotic solvents, implying solvents with functional groups containing oxygen (O), sulphur (S), or nitrogen (N), can act as Lewis bases in the vicinity of the Lewis acid PbI 2 . They can be classified into O-donors, like DMSO, NMP, or Figure 1.…”

High‐Efficiency Perovskite Solar Cells Using Molecularly Engineered, Thiophene‐Rich, Hole‐Transporting Materials: Influence of Alkyl Chain Length on Power Conversion Efficiency

“…The field is indeed dominated by the HTM 2,2´,7,7´-tetrakis(N,N-di-pmethoxyphenylamine)-9,9´-spirobifluorene (spiro-OMeTAD) and by the even more expensive poly[bis(4-phenyl)-(2,4,6-trimethylphenyl)amine] (PTAA). [13,14] Developing new HTM molecules through inexpensive synthetic routes and without needing of tedious purification steps remains therefore as a primary goal. Finding HTMs that exhibit holeinjection and transport properties similar to spiro-OMeTAD and PTAA, and closely match the valence band edge of the perovskite is the key for avoiding any loss in electrical potential and charge recombination.…”

Advances in Inkjet‐Printed Metal Halide Perovskite Photovoltaic and Optoelectronic Devices

“…Details of these procedures are discussed in Section . It has been shown that it is advantageous to use strongly coordinating Lewis base solvents such as DMSO and NMP for PbI 2 deposition, as this results in PbI 2 ‐solvent adducts that can be converted into perovskites by intramolecular exchange when exposed to the monovalent cation, forming large uniform crystals in the process . For IJP, the results suggest that a two‐step conversion process is most suitable on mesoporous contact layers, as this improves pore‐filling and surface coverage .…”