State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources , North China Electric Power University , Beijing 102206 , P. R. China.
Energy System Engineering Department , Sukkur IBA University , Sukkur 65200 , Pakistan.
ACS Appl Mater Interfaces. 2019 Sep 25;11(38):34964-34972. doi: 10.1021/acsami.9b11229. Epub 2019 Sep 12.
Elimination of interfacial charge trapping is still a challenge for promoting both efficiency and operational stability of organic-inorganic perovskite solar cells (PSCs). Herein, an effective interface dipole, trimethylamine oxide (TMAO) regarded as a connecting bridge, is inserted between the electron transport layer (ETL) and the perovskite layer to suppress charge accumulation and fabricate highly efficient and stable PSCs. As demonstrated by energy level alignment and morphology characterization, TMAO dipoles could achieve a decreased energetic barrier of electron transport and substantial padding of perovskite in the mesoporous ETL. Thus, they facilitate the charge transfer and reduce trapped charge densities as well as recombination centers at the interface between perovskite and ETL. These desirable properties improve the device efficiency to 21.77% and weaken the hysteresis index almost to 0. More importantly, the stability of the unencapsulated PSCs is remarkably enhanced. The findings provide valuable insights into the role of a dipolar molecule in boosting the performance of PSC devices.
消除界面电荷俘获仍然是提高有机-无机钙钛矿太阳能电池（PSC）效率和运行稳定性的挑战。在此，我们在电子传输层（ETL）和钙钛矿层之间插入了一种有效的界面偶极子，即三甲基氧化胺（TMAO），将其作为连接桥，以抑制电荷积累，制备高效稳定的 PSC。通过能级对准和形貌表征，TMAO 偶极子可以实现电子传输的能垒降低和介孔 ETL 中钙钛矿的实质性填充。因此，它们促进了电荷转移，降低了钙钛矿和 ETL 界面处的俘获电荷密度和复合中心密度。这些理想的特性将器件效率提高到了 21.77%，并将滞后指数几乎降低到 0。更重要的是，未封装的 PSC 的稳定性得到了显著提高。这些发现为理解偶极分子在提高 PSC 器件性能方面的作用提供了有价值的见解。
