Preparation And Properties Of Cationic Polyelectrolytes With Sulfonate Counterions

Polymer solar cells?PSCs?have gained extensive attention due to their potential applications as clean energy sources and the possibility of large–area fabrication.Electron transport layers?ETLs?play a key role due to their fundamental importance for electron extraction and transport process.Therefore,this thesis focuses on the introduction of alkylsulfonate counterions into cationic polyelectrolytes,and explores the effects of different alkylsulfonate anions on the properties of the electron transport layer materials.The main content includes two aspects:1. Three cationic polyelectrolytes PEIE–MSB,PEIE–DIB and PEIE–OH,containing methylsulfonate,iodide ion,and hydroxide ion respectively,were prepared.These polymer materials were used as the electron transport layer of the inverted PSCs based on PTB7-Th:PC₇₁BM.The results show that PEIE-MSB-based device has the highest PCE of 10.30%,meanwhile,the PEIE-DIB-and PEIE-OH-based devices have PCE of 9.72%and 10.07%,respectively.The electron transport performance of PEIE-MSB-based PSC is better than that of PEIE-DIB-based and PEIE-OH-based,due to better phase morphology and interface contact,and fewer interface defects.In addition,PEIE-MSB was applied to inverted PSCs with PM6:IT-4F and PM6:Y6 as active layers,and also showed excellent performance with PCE of 13.41%and 15.83%,respectively.These fully illustrated that PEIE cross-linked polymers containing alkylsulfonate anions is a kind of high performance ETL that can be applied in PSCs.2. The effects of different alkyl sulfonate anions on the properties of polymer electron transport layers were investigated.Three cationic polyelectrolytes PEIE–MSB,PEIE–ESB and PEIE–BSB,containing methylsulfonate,ethylsulfonate,and benzylsulfonate respectively,were prepared for cathode interface layers?CILs?via one-step reaction with 1,4–butanediol dialkylsulfonate and polyethyleneimine ethoxylate as the reactants.The results showed that PEIE-MSB and PEIE-ESB with smaller counter ions have higher electron extraction efficiency,higher electron mobility and better photovoltaic performance than PEIE–BSB with larger counterion.The inverted PTB7–Th:PC₇₁BM PSCs with PEIE–ESB under the thickness of 9 nm,18 nm and 30 nm achieved PCEs of 10.44%,9.96%and 9.23%,respectively.In addition,PSCs based on PM6:Y6 as active layer and PEIE-ESB as ETL showed a high PCE of 15.69%,which is slightly higher than the PCE of PSCs with Zn O?15.37%?.Therefore,this work shows that different alkylsulfonate anions can affect the performance of polymer electron transport layers.