Organic Polymers as Additives in Perovskite Solar Cells

Abstract

The wide field of polymer chemistry has recently encountered the unique, promising field of perovskite solar cells (PSCs). Thanks to their chemical versatility, the possible applications of organic polymers within solar devices have been highly diversified as charge-transporting materials, of either hole or electrons, or as additives, being these blended into the designed layer or used as a buffer layer. The use of different organic polymers as additives has demonstrated to be beneficial for the device performance and stability, thanks to an improved morphology of the thin layers and to their assistance in the charge transport. This perspective intends to provide the reader with a clear viewpoint on the role that polymers play as additives in PSCs. Thus, the most important examples describing the use of these macromolecules as additives in each of the possible target layers within PSCs are reported. Understanding the role played by the polymer together with the necessary chemical functionalities that provide each role within the solar cells is of primary importance in the future design of polymeric materials to be used in PSCs. Therefore, with this perspective article, we expect to contribute in the rational design of next-generation organic polymers suitable to surpass the current state of the art in PSCs.

Molecular Design and Cost-Effective Synthesis of Tetraphenylethene-Based Hole-Transporting Materials for Hybrid Solar Cell Application

“…Hybrid perovskite solar cells (PSCs) have become an intriguing area of photovoltaic research due to their high charge carrier mobility, tunable band gap energy, low exciton binding energy, low cost, and high power conversion efficiency. − Conventionally, a PSC consists of light harvesting materials, an electron transport layer (ETL), a hole transport layer (HTL), and electrodes. Perovskites are excited by solar light, and the formed excitons are transferred down to the ETL along with the regeneration of the perovskite by the HTL.…”

Molecular design for perovskite solar cells

“…Secondly, the additive molecules can be molecularly engineered to alter the resulting halide perovskite crystal structures, morphologies, and roughness; this is often accompanied with the formation of intermediate compounds in the precursor solution 76‐78 . Many molecular additives compatible with the halide perovskites are available, including those based on small organic molecules, fullerene polymers, and organometallic halide salts, which significantly influence the perovskite morphology and crystallization kinetics 79‐83 . The following aspects have been pointed out to effectively design the molecular additives for perovskite solar cells from the molecular engineering point of view.…”

A functionalized polyamide acid additive for perovskite solar cells with high efficiency and stability

“…Furthermore, polymer additives possess more excellent properties of water blocking, thermal resistance, and mechanical stability, which are beneficial for enhancing the operational stability of PSCs. 32 Polymers with hydroxyl groups (Scheme 1), like polyethylene glycol (PEG), 33 can form hydrogen bonds with MAPbI 3 and improve the crystal morphology of perovskite. In addition, a series of polymers with different functional groups, such as poly(propylene carbonate) (PPC, 34 carbonate groups), polycaprolactone (PCL, 35 carboxyl groups), polyvinyl butyral (PVB, 36 butyral groups), polyvinyl alcohol (PVA, 36 hydroxyl groups), polymethyl methacrylate (PMMA, 37 acrylate groups), poly(ethylene- co -vinyl acetate) (EVA, 38 acetate groups), and poly(acrylic acid) (carboxylic acid groups), were used as additives in the perovskite, respectively.…”