Hybrid Lead-Halide Polyelectrolytes as Interfacial Electron Extraction Layers in Inverted Organic Solar Cells

Abstract

A series of lead-halide based hybrid polyelectrolytes was prepared and used as interfacial layers in organic solar cells (OSCs) to explore their effect on the energy band structures and performance of OSCs. Nonconjugated polyelectrolytes based on ethoxylated polyethylenimine (PEIE) complexed with PbX2 (I, Br, and Cl) were prepared as polymeric analogs of the perovskite semiconductors CH3NH3PbX3. The organic/inorganic hybrid composites were deposited onto Indium tin oxide (ITO) substrates by solution processing, and ultraviolet photoelectron spectroscopy (UPS) measurements confirmed that the polyelectrolytes allowed the work function of the substrates to be controlled. In addition, X-ray photoelectron spectroscopy (XPS) results showed that Pb(II) halide complexes were present in the thin film and that the Pb halide species did not bond covalently with the cationic polymer and confirmed the absence of additional chemical bonds. The composite ratio of organic and inorganic materials was optimized to improve the performance of OSCs. When PbBr2 was complexed with the PEIE material, the efficiency increased up to 3.567% via improvements in open circuit voltage and fill factor from the control device (0.3%). These results demonstrate that lead-halide based polyelectrolytes constitute hybrid interfacial layers which provide a novel route to control device characteristics via variation of the lead halide composition.

Stabilizing Non‐Fullerene Organic Photodiodes through Interface Engineering Enabled by a Tin Ion‐Chelated Polymer

“…It is worth noting that the roughness of the typical counterparts (ZnO, SnO 2 , and PEIE) thin films can match the level of literature. [ 45 , 46 ] The experimental results demonstrate that PEIE‐Sn can effectively polish the surface roughness of ITO, and the negligible variation in roughness at different regions indicates that the film is uniform, which benefits ameliorating the quality of the active layer and allows for better charge extraction. Additionally, PEIE‐Sn has a much larger contact angle as compared to its counterparts (Figure S13b , Supporting Information), which may be beneficial for improving the uniform, conformal, and close contact between PEIE‐Sn and the photoactive layer.…”

Cathode Interlayer Based on Naphthalene Diimide: A Modification Strategy for Zinc-Oxide-Free Inverted Organic Solar Cells

“…Organic solar cells (OSCs) have drawn a lot of interest as a low-cost renewable energy source with large-scale capabilities on various substrates. − As a result, power conversion efficiencies (PCEs) have significantly improved, which have exceeded 20%. − The advancements were acquired by the discovery of an effective active layer, the modification of photoactive layer morphology, and the enhancement of interface properties …”

Automatic formation of electron transport layer in BHJ solar cells using phenothiazine-based conjugated small molecular electrolytes

“…[7][8][9][10][11] In an inverted BHJ solar cell, interfacial engineering between the indium tin oxide (ITO) bottom electrode and the photoactive layer is considered a feasible method to improve the device efficiency, and modification of the electron transport layer (ETL) is a vital part of interfacial engineering. [12][13][14][15][16][17][18] ETL is a cathode interface layer and should not only form a good ohmic contact with the active layer to facilitate the collection of charges but should also have proper energy levels for efficient exciton separation and charge transport. [19][20][21][22][23][24] Zinc oxide (ZnO) is one of the most popular ETL materials because of its excellent electron mobility, high visible-light transparency, and easy preparation.…”