Carbon-based mesoscopic perovskite solar cells (MPSCs) are becoming one of the most competitive photovoltaic technologies owing to their lower manufacturing cost and excellent stability. In this work, methylammonium acetate (MAAc), an ionic liquid additive, is added into methylammonium lead triiodide (MAPbI 3 ) perovskite and is used to fabricate high-performance MPSCs. Systematic and detailed studies have shown that the MAAc interacts with PbI 2 preferentially to form a MAPbI 3−x (Ac) x intermediate phase that can effectively control the crystallization kinetics of MAPbI 3 in the triple-mesoscopic layer. MAPbI 3 films with an appropriate amount of MAAc exhibit higher crystallinity, lower defect density, and dense pore filling, which effectively reduce carrier nonradiative recombination loss in MPSCs. As a result, a champion power conversion efficiency (PCE) of 13.54% is obtained based on the optimized MAAc-engineered MPSCs. The PCE is 24% higher than 10.90% of the control devices. Moreover, unencapsulated MAAc-engineered MPSCs retain 90% of their initial PCE after being stored in the dark for 50 days under ambient atmosphere, which demonstrates much better air stability than control devices. This work provides an effective strategy for developing efficient and stable carbon-based MPSCs with an eco-friendly ionic liquid additive.

No abstract

Additive strategies play a critical role in improving the performance of organic solar cells (OSCs). There are only a few reports on the application of solid additives for OSCs, which leaves a large space for further improvement of solid additives and further study on the relationship between material structure and property. PM6:BTP-eC9-based organic solar cells (OSCs) were prepared by using a small molecule BTA3 as a solid additive, and a high energy conversion efficiency of 18.65% is achieved. BTA3 has good compatibility with the acceptor component (BTP-eC9) and optimizes the morphology of the thin films. Moreover, the introduction of a small amount of BTA3 (5 wt %) effectively promotes exciton dissociation and charge transfer and suppresses charge recombination, and the relationship between the BTA3 content and the device parameter is deeply revealed. The use of BTA3 in the active layers is an attractive and effective strategy for high-performance OSCs.

In this work, a series of ternary organic solar cells (OSCs) were prepared with polymer PM6 as a donor and two non-fullerene materials, BTP-eC9 and ITIC-Th, with excellent compatibility as acceptors. The open-circuit voltage (V OC ) of ternary OSCs is found to monotonically increase with increasing content of ITIC-Th, implying the formation of an alloying state between BTP-eC9 and ITIC-Th. Furthermore, the incorporation of ITIC-Th can effectively minimize energy loss, which effectively improves the V OC of ternary OSCs. Consequently, a remarkable power conversion efficiency (PCE) of 18.7% with a short-circuit current density (J SC ) of 28.0 mA cm −2 , a V OC of 0.87 V, and a fill factor (FF) of 77.0% is achieved from the optimal ternary OSCs with 15 wt % ITIC-Th in acceptors. Comprehensive characterizations show that the enhanced J SC and FF are likely due to enhanced photon harvesting, effective exciton dissociation, and balanced charge transport in the optimal ternary active layers. The findings provide a hopeful way to further improve the OSC performance by employing a ternary strategy with two compatible non-fullerene materials as acceptors.

No abstract