Search

Planar-structure perovskite solar cells have attracted more and more attention, because their simple and low-temperature preparation processing. However, the performance of perovskite solar cells is currently limited by defect-induced recombination at interfaces between perovskite and charge transport layers. In this work, a filmy poly methyl methacrylate (PMMA) layer introduced in Perovskite/Spiro-OMeTAD interface to passivate the interfacial and interganular defects, by which a high open-circuit voltage (1.18 V) is acquired, and the optimal device shows a steady-state power conversion efficiency of 20.5% and negligible hysteresis. Femtosecond transient absorption measurement confirms a significant reduction in non-radiative recombination for passivated devices. Mott-Schottky measurement indicates improved flat band potential and carrier density in passivated devices, consisting with the increased voltage. In addition, PMMA film can protect perovskite film from moisture and oxygen erosion. The unsealed device still maintains 95% of the initial efficiency under ambient conditions with 60% relative humidity for one month. This approach solves one of the main limitations of interfacial recombination and shows its potential to improve the performance of perovskite solar cells in the future. • An ultrathin polymer film is used to passivate the interfacial and intergranular defects in PSCs. • The modified PSC shows a steady-state power conversion efficiency of 20.5% and negligible hysteresis. • The fs-TA measurement is implemented for analyzing transfer and recombination dynamics of the photo-generated carrier. • The PMMA film plays the role of encapsulation which could protect perovskite film from moisture and oxygen erosion. [ABSTRACT FROM AUTHOR]

Fullerene‐free organic solar cells (OSCs) are fabricated using a blend of J61 polymer as donor and the blend of m‐3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene)‐indanone))‐5,5,11,11‐tetrakis(4‐hexyl phenyl)‐dithieno[2,3‐d:2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′] dithiophene (ITIC) and ITIC‐Th as electron acceptor. The blend of m‐ITIC and ITIC‐Th as electron acceptor due to the similar lowest unoccupied molecular orbital energy levels and good compatibility among J61, m‐ITIC, and ITIC‐Th, are beneficial for the small energy barrier at the m‐ITIC:ITIC‐Th interface. Simultaneously, the ternary photoactive layer can maintain the optimize film morphology and beneficial to ensure effective suppression of charge recombination at the three kind materials interface. The power conversion efficiency of ternary OSCs achieves to 12.57% when the blend of m‐ITIC:ITIC‐Th (the ratio of m‐ITIC:ITIC‐Th is 40:60) as electron acceptor, with enhanced open‐circuit voltage (VOC) of 0.91 V, short‐circuit current densities (JSC) of 19.94 mA cm−2, and fill factor of 69.6%. Moreover, the optimal ternary OSCs show enhanced thermal stability and photostability than the binary OSCs. This study indicates that the blend of m‐ITIC and ITIC‐Th as electron acceptor and J61 as donor is a promising strategy to fabricate high performance and stable OSCs. [ABSTRACT FROM AUTHOR]