Despite tremendous progress in optoelectronic devices using lead perovskite (CH3NH3(+)PbI3(-)), there has been a paucity of mechanistic information on how photoactive micron-sized crystals of lead perovskite grow from a mixture of a layered crystal of lead(II) iodide and methylammonium iodide mediated by a polar solvent, DMSO or DMF. We report here that the whole process of the lead perovskite synthesis consists of a series of equilibria driven by reversible solvent participation involving a polymeric strip of plumbate(II) oligomer as a key intermediate. A significant finding includes quick decomposition of perovskite crystal upon exposure to DMSO or DMF at room temperature, where the solvent molecules act as a base to remove acidic ammonium iodide from the perovskite crystal. This observation accounts for the difficulty in controlling perovskite solar cell fabrication. Overall, the polar solvent is indispensible first to degrade a 2-D sheet of crystals of lead(II) iodide into 1-D fibrous intermediates and then to promote Oswald ripening of perovskite crystals. The detailed chemical information provided here will help to rationalize the photovoltaic device studies that have so far remained empirical and to open a new venue to a developing field of microscale lead perovskite devices, as illustrated by fabrication of photovoltaic devices and photodetectors.

COMMUNICATIONThis journal is COMMUNICATION This journal is Table 1. Details of the photovoltaic performance of the solar cells using different HTLs, and the conductivity and HOMO level of different HTL films. a P3HT dissolved in 1 ml of chlorobenzene, b Li-TFSI dissolved in 6.8 µl of acetonitrile, c 10.2 µl D-TBP was added to the P3HT:Li-TFSI mixture solution, d The HOMO level was estimated from photoelectron yield spectroscopy analysis. A table of contents entryA 99.5% void-free perovskite layer with doped-P3HT hole-transporting layer showed highest PCE among the P3HT based hybrid solar cells.

Pathogen effector proteins are delivered to host cells to suppress plant immunity. However, the mechanisms by which effector proteins function are largely unknown. Here we show that expression of XopP Xoo , an effector of rice pathogen Xanthomonas oryzae pv. oryzae, in rice strongly suppresses peptidoglycan (PGN)-and chitin-triggered immunity and resistance to X. oryzae. XopP Xoo targets OsPUB44, a rice ubiquitin E3 ligase with a unique U-box domain. We find that XopP Xoo directly interacts with the OsPUB44 U-box domain and inhibits ligase activity. Two amino-acid residues specific for the OsPUB44 U-box domain are identified, which are responsible for the interaction with XopP Xoo . Silencing of OsPUB44 suppresses PGN-and chitin-triggered immunity and X. oryzae resistance, indicating that OsPUB44 positively regulates immune responses. Thus, it is likely that XopP Xoo suppresses immune responses by directly interacting with and inhibiting a positive regulator of plant immunity.

n-Type doping of a polymeric electron-transporting layer in a perovskite solar cell doubles the performance of the device.