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As a famous hole transporting material, nickle oxide (NiOx) has drawn enormous attention due to its low cost and superior stability. However, the relatively low conductivity and high-density surface trap states of NiOx severely limit device performance in solar cell applications. Interfacial engineering is an efficient approach to achieve remarkable hole-transporting performance by surface passivation. Herein, the efficient NiOx hole transport layer was prepared by surface passivation engineering strategy via facile solution processes with cesium iodide (CsI). It is demonstrated that CsI plays a super-effective dual-function role in inverted solar cell device: On one hand, the presence of CsI hugely passivates the surface trap states at the NiOx/perovskite interface along with obviously improved conductivity by the incorporated Cs+; on the other hand, the ions immigration is significantly suppressed by the presence of I ion for high-quality perovskite films, resulting in a stable contact interface. The ameliorative interface leads to largely reduced carrier non-radiative recombination, attributing to boosted carrier extraction efficiency. As a result, decent power conversion efficiency (PCE) of 18.48% with a noticeable fill factor (FF) beyond 80% was achieved. This facile and efficient surface engineering approach with dual-function shows excellent potential for the design of high-performance functional interfacial modification layer to achieve high-performance solar cells. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) based on planar SnO2 (p‐SnO2) demonstrate excellent performance due to the superior properties of SnO2 as electron transporting layer (ETL). However, at present mesoporous SnO2 (m‐SnO2) still lags behind p‐SnO2 due to problems in the fabrication process of m‐SnO2. In this paper, a new strategy for preparing m‐SnO2 ETL is introduced which owns two valuable features: First, it applies a low temperature process to make mesoporous structure, which favors preserving the pristine properties of the raw SnO2 nanocrystals. Second, the degree of porosity and roughness of the m‐SnO2 layer can be well controlled, making it friendly to the following deposition process of PSCs. The performance of the PSCs based on the m‐SnO2 ETL prepared from this strategy shows an obvious improvement which is mainly from the improvement in Jsc and FF, suggesting a higher carrier collection efficiency for the m‐SnO2 ETL. The relevant characterizations including PL, TRPL, EIS, and KPFM confirm that the m‐SnO2 ETL possesses stronger electron extraction capability than the p‐SnO2 ETL. Hence, the proposed strategy can manifest the advantages of m‐SnO2 ETL meanwhile refrain its negative impacts, and thus promote the progress of the m‐SnO2 ETL‐based PSCs. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) have attracted intense research interest in the last few years due to their excellent properties. However, the trap states at grain boundary (GBs) of perovskite films lead to charge recombination and perovskite film decomposition, which deteriorate the stability of PSCs. It has been demonstrated that the GBs passivation is an effective way to eliminate trap states and enhance the stability of PSCs. In this work, ethyl acetate (EA) and chlorobenzene (CB) were used as anti-solvent, mixing with phenyl-C61-butyric acid methyl ester (PC61BM) to replace pure antisolvent CB to control the GBs passivation of perovskite film. Meanwhile, enhanced interfacial hydrophobic characteristic effectively restricted the penetration of moisture. Correspondingly, with optimizing the volume ratio of EA/CB, the power conversion efficiency of PSCs based on CH3NH3PbI3 increased from 14.4 to 16.1% and the stability is greatly improved. This shows the adoption of a mixed solvent for EA and CB contained PC61BM as the solute can be used as an efficient tactic to passivate the surface crystal boundary, improve charge carrier transportation and device performance. [ABSTRACT FROM AUTHOR]