Three novel species of Russula Pers. subg. Compactae (Fr.) Bon from southern China are described with morphological evidence and phylogenetic analyses based on ITS and the concatenated partial LSU, mtSSU, rpb1, rpb2 and tef1 gene sequences. All three species possess sparse and broad lamellae. Russula latolamellata Y.Song & L.H.Qiu, sp. nov., is characterized by its cracking, black-tan pileus, scarlet-turning context on bruising and absence of pileocystidia and caulocystidia. Russula nigrocarpa S.Y.Zhou, Y.Song & L.H.Qiu, sp. nov., can be distinguished by its off-white lamellae, small basidiospores, hymenial cystidia and pileocystidia of various forms, often with forked apices and by its gelatinous pileipellis. Russula ochrobrunnea S.Y.Zhou, Y.Song & L.H.Qiu, sp. nov., is characterized by its cracking, grayish brown pileus with striate margin, light-brown lamellae whose edges turn dark-brown when mature, small basidiospores and slightly flexuous ormoniliform hymenial cystidia. Their detailed morphological features and phylogenetic positions are discussed and compared among closely related species.

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The development of hole-transporting materials (HTMs) that can passivate defects in perovskite is of great significance in improving the efficiency and long-term stability of perovskite solar cells. To date, the investigation on HTMs mainly focus on exploring new structures, while molecular configuration is seldomly concerned. In this work, two small molecules are developed as HTMs with benzil and phenanthrene quinone as the core structure, respectively. With similar structure and the same defect passivation groups, whereas, the two molecules exhibit different configurations, thus distinct properties. Compared to 3,6-bis(3,6-bis(bis(4-methoxyphenyl)amino)-9H-carbazol-9-yl) phenanthrene-9,10-dione (PQ) with a rigid core structure, the benzil group in 1,2-bis(4-(3,6-bis(bis(4-methoxyphenyl)amino)-9H-carbazol-9-yl)phenyl)ethane-1,2-dione (DB) is flexible and can adjust molecular configuration to efficiently interact with the underlying perovskite material, which is confirmed from both experimental results and theoretical simulations. The DB-based device exhibits a high power conversion efficiency of 22.21% with excellent long-term stability, superior to the PQ-based device (20.22%). This study demonstrates that molecular configuration engineering will directly affect the properties of hole transport materials, as well as their interactions with perovskite, which should also be taken into consideration when devising HTMs.

In conventional (n‐i‐p) perovskite solar cells (PSCs), spiro‐OMeTAD is the most widely used hole‐transporting material (HTM), which contributes to the current state‐of‐the‐art efficiency. Suffering from the low conductivity, dopants such as LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) and tBP are usually required to achieve excellent hole transport properties in spiro‐OMeTAD. Nevertheless, the hygroscopicity and the migration of Li+ during device operation severely affect the device's stability. To address the aforementioned issue, a 12‐crown‐4‐based organic semiconductor (CDT) is synthesized and applied in PSCs. Notably, CDT is simultaneously doped in spiro‐OMeTAD and perovskite layer through the antisolvent method. In this way, the strong “host‐guest” interaction between crown ether and Li+ effectively inhibits its migration both in the hole transporting layer (HTL) and at the perovskite/HTM interface. Furthermore, the carbazole diphenylamine group in CDT facilitates hole transport, and meanwhile improves the hydrophobicity of the HTL. In addition, CDT added into the perovskite layer is also able to passivate defects by interacting with the undercoordinated Pb2+. In light of the aforementioned advantages, the CDT‐based device shows a high power conversion efficiency approaching 23%, with excellent long‐term stability.

Spiro-OMeTAD has been playing an indispensable role in highly-efficient perovskite solar cells (PSCs). However, a long air oxidation progress is usually required, which is harmful to the device stability. Herein,...