Interfacial Regulation And Performance Improvement In Organic Solar Cells And Perovskite Solar Cells

Organic solar cells?OSCs?and perovskite so lar cells?PSCs?have become a hot topic due to their advantages in light weight,portable,flexibility and roll-to-toll large scale production.Great progress has been made in the past few years.The power conversion efficiency?PC E?has exceeded 10% for OSCs and 22% for PSCs.Nowadays,a so-called sandwiched devices structure is usually adopted in these devices and the interfacial regulation between electrode and active layer plays a critical role in device performance,which is necessary for high performance solar cel s.Here,focusing on the common problems in OSCs and PSCs,we mainly studied the application of ionic organic materials in solar cells as interlayers and proposed non-conjugated small-molecule ionic interlayer materials,which promotes the PCE to 9%.Importantly,we found and in-depth studied the impact of external bias on OSCs performance with ionic interlayer and also investigated the hysteresis of PSCs under external bias.In addition,the app lication of polyelectrolytes interlayer and the optimization in morphology of perovskite films were also in-depth studied,increasing the PCE of inverted PSCs to 19%.The main results were listed as follows:1.Through using fullerene derivative with polar groups as cathode interlayer,electrons transport can be facilitated while holes are blocked.The final devices performance is enhanced from 4.83% to 7.92%,which is even better than that of traditional Ca/Al devices.2.Using ionic interlayers in OSCs,the device performance depends on the measuring conditions like scan voltage size and direction,which is caused by ions motion in interlayers.Through external bias treatment to promote ion rearrangement in interlayers,the device performance is increased from ⁶% to 9%,which was the highest PCE of inverted OSCs with small molecule ionic interlayer.3.Ions motion existed in perovskite solar cells?PSCs?and external bias could effectively affect the device performance.The device performance was impressively improved from less than 1% to exceeding 8% after external bias treatment.In addition,the PSCs showed severe hysteresis.Through interfacial regulation to avoid direct contact between perovskite films and metal electrode,the device hysteresis can be effectively suppressed.4.Optimization in device interface and film morphology of perovskite was an effective method to achieve high performance inverted PSCs.By using polyelectrolytes material with deep HOMO energy level as anode interlayer,the device efficiency was improved from 13.7% to 16.6%.And the efficiency can be further increased to 19% through the morphology control of perovskite films,which is among the highest PCE for perovskite solar cel s without TiO₂.