Improved performance and life time of inverted organic photovoltaics by using polymer interfacial materials

Two-in-one: cathode modification and improved solar cell blend stability through addition of modified fullerenes

“…We anticipate that during deposition of the active layer, the amine-functionalised fullerene derivative tends to selfassemble at the interface of the ITO cathode. 30 This self-organisation is driven by chemisorption of the nitrogen functional groups onto the ITO and the molecules modify the surface energy of the ITO electrode. We inferred the change in substrate surface energy due to absorption of the amine-functionalised fullerene by measuring the water contact angle on ITOsubstrates.…”

“…The amine group on PCBA is similar to the one used on interlayer polymers previously published by us. 29,30 This type of amine group has been shown to chemisorb to a number of different substrates, including ITO, 31 and is therefore likely to induce a self-assembly of PCBA at the ITO-cathode. Importantly, it has recently been shown that a tertiary-amine functionalised fullerene selfassembles on the ITO-cathode of an organic solar cell when codeposited in a binary or ternary mixture with the donor polymer poly(3-hexylthiophene).…”

Vertical Composition Distribution and Crystallinity Regulations Enable High-Performance Polymer Solar Cells with >17% Efficiency

“…As a potential candidate for renewable energy for future energy sources, polymer solar cells (PSCs) have gained a great deal of attention in recent decades due to their unique advantages, such as their potential for low-cost production via high-throughput roll-to-roll (R2R) processing technology, mechanical flexibility, and light weight. − The one-step solution process of the blend of electron donors and acceptors that are dissolved in a single solution has been broadly employed to produce a bulk heterojunction (BHJ) photoactive layer, and these types of PSCs are reasonably named BHJ polymer solar cells . Benefiting from combined efforts including novel photovoltaic materials, − ingenious photoactive layer morphology control, , and efficient electrode interfacial materials, ,, the state-of-the-art BHJ PSCs have reached power conversion efficiencies (PCEs) of 16–18% recently. − Although great success has been obtained in BHJ PSCs, ,− the one-step solution process technology is not an ideal method for the fabrication of efficient PSCs because (i) the formation of the BHJ morphology is an extremely complicated process, − (ii) the BHJ morphology of the photovoltaic active layer is strongly dependent on the history of the blend solution, , (iii) the vertical component distribution is difficult to control precisely, ,, and (iv) the crystallizations of the donor and acceptor can be disturbed inevitably by each other during the solidification of the blend solution. , To further realize more efficient and stable polymer solar cells and make this solar technology attractive to industry, the aforementioned issues should be taken into consideration.…”

Alcohol-Soluble Conjugated Polymers as Cathode Interlayers for All-Polymer Solar Cells

“…A CIM also serves as a diffusion barrier to stop metal ions from diffusing into the active layer . Some commonly used CIMs are lithium fluoride (LiF), zinc oxide (ZnO), and certain compounds containing aliphatic tertiary amine units. − The most common types of amine-containing CIMs are polymers with amine pendant groups such as polyethylenimine (PEI) and polyethylenimine ethoxylated (PEIE) and conjugated polymers with pendant amine groups such as poly­[(9,9-bis­(3′-( N , N -dimethylamino)­propyl)-2,7-fluorene)- alt -2,7-(9,9-dioctylfluorene)] (PFN) . These compounds can be ionized to create even more water/alcohol soluble materials with better charge-transporting properties. , In some cases they have been cross-linked to further improve stability .…”