Water/Alcohol Soluble Thickness-Insensitive Hyperbranched Perylene Diimide Electron Transport Layer Improving the Efficiency of Organic Solar Cells

Abstract

The electron transport layer (ETL) is very crucial for enhancing the device performance of polymer solar cells (PSCs). Meanwhile, thickness-insensitive and environment-friendly water/alcohol soluble processing are two essential requirements for large-scale roll-to-roll commercial application. Based on this, we designed and synthesized two new n-type ETLs with tetraethylene pentamine or butyl sulfonate sodium substituted tetraethylene pentamine as the branched side chains and high electron affinities perylene diimide (PDI) as the central core, named as PDIPN and PDIPNSO3Na. Encouragingly, both PDIPN and PDIPNSO3Na can effectively reduce the interfacial barrier and improve the interfacial contact. In addition, both of them can exhibit strong n-type self-doping effects, especially the PDIPN with higher density of negative charge. Consequently, compared to bare ITO, the PCE of the devices with ITO/PDIPN and ITO/PDIPNSO3Na ETLs has increased to 3–4 times. Our research results indicate that n-type self-doping PDI-based ETL PDIPN and PDIPNSO3Na could be promising candidates for ETL in environment-friendly water/alcohol soluble processing large-scale PSCs.

N-Type Self-Doped Hyperbranched Conjugated Polyelectrolyte as Electron Transport Layer for Efficient Nonfullerene Organic Solar Cells

“…Since a good charge transfer between layers can be achieved by tuning the interfacial contact. The electron transport layers (ETLs) are always introduced to optimize the interfacial contact. − …”

Molecular strategy towards ROMP-derived hyperbranched poly(olefin)s featuring various π-bridged perylene diimides

“…In general, the AFM characterization manifests that hyperbranched poly(oxanorbornene imide)s bearing (π-bridged)perylene diimides are having smooth and homogenous surface in comparison to other examples of perylene diimide-based hyperbranched polymers prepared using different methodolgies. 86,87…”

Bay-Functionalized Perylene Diimide Derivative Cathode Interfacial Layer for High-Performance Organic Solar Cells

“…The functionalization of the imide position has little impact on the photoelectric properties of PDI molecules, but it is effective in regulating molecular aggregation and solubility. Moreover, it is proven that bay modification of PDI is the most effectual strategy for suppressing molecular aggregation. , From this point of view, it is scientifically feasible to develop a bay site-modified PDI derivative as a CIM, which should tend to reduce flatness and molecular aggregation and have excellent charge transport and device performance. − …”

“…Researchers have developed numerous n-type organic semiconductors considering their preferable electron affinities and electron mobilities. Especially, perylene diimides (PDIs) have the merits of low cost, strong function tunability, high conductivity, solubility in alcohol and water, and maintenance of excellent interfacial interactions with the active layer. − …”

“…Moreover, it is proven that bay modification of PDI is the most effectual strategy for suppressing molecular aggregation. 23,41 From this point of view, it is scientifically feasible to develop a bay site-modified PDI derivative as a CIM, which should tend to reduce flatness and molecular aggregation and have excellent charge transport and device performance. 42−44…”