The synthetic route and properties of three 2D hybrid organic/inorganic lead iodide perovskite materials are reported. The 2D perovskites were synthesized from the reaction between PbI 2 and the di-cations of 1,4diaminobutane, 1,6-diaminohexane, and 1,8-diaminooctane. The resulting products were [NH 3 (CH 2 ) 4 NH 3 ] PbI 4 (BdAPbI 4 ), [NH 3 (CH 2 ) 6 NH 3 ]PbI 4 (HdAPbI 4 ), and [NH 3 (CH 2 ) 8 NH 3 ]PbI 4 (OdAPbI 4 ). Structural characterization shows that two dimensional perovskite structures were formed with inorganic structural planes separated by organic layers. Absorption spectra show band gaps of 2.37 eV (BdAPbI 4 ), 2.44 eV (HdAPbI 4 ), and 2.55 eV (OdAPbI 4 ). The 2D perovskite materials were investigated as light absorbing materials in solid state solar cells.The best performing material under moist, ambient conditions was BdAPbI 4 (1.08% efficiency), which was comparable to methylammonium Pb(II) iodide (MAPbI 3 ) solar cells (2.1% efficiency) manufactured and studied under analogous conditions. When compared to MAPbI 3 , the 2D materials have larger band gaps and lower photoconductivity, while BdAPbI 4 based solar cells shows a comparable absorbed photon-to-current efficiency as compared to MAPbI 3 based ones. † Electronic supplementary information (ESI) available: Tables S1-S4 including atomic parameters of the structure of the three new materials, Fig. S1 and S2, two 2D structures of butyl 1,4-diammonium lead iodide and octyl 1,8-diammonium lead iodide along the three crystallographic axes. Tables S5-S11 and Fig. S3-S9 describe structural and photochemical characterization. CIF les for the structures are available at the Cambridge Crystallographic Data Center (CCDC) referring to the deposition numbers 1420433 and 1420434 for HdAPbI 4 and OdAPbI 4 , respectively. See

Herein we report on integrated photoelectrolysis of water employing organic metal halide (OMH) perovskite material. Generic OMH perovskite material and device architecture are highly susceptible to degradation by moisture and water. We found that decomposition of perovskite devices proceeds by water ingress through pinholes in upper layers and is strongly affected by applied bias/light and electrolyte pH. It was also found that a pinhole-free hole transport layer (HTL) could significantly enhance the stability of the perovskite photoelectrode, thereby extending the photoelectrode lifetime to several tens of minutes, which is an unprecedented record-long operation. Furthermore, a carbon nanotube (CNT)/polymer composite layer was developed that can effectively protect the underlying perovskite layer from electrolyte molecules.

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A carbon electrode with low cost and high stability exhibited competitiveness for its practical application in organic–inorganic hybrid perovskite solar cells (PSCs). Nonetheless, issues such as poor interface contact with an adjacent perovskite layer and obvious hysteresis phenomenon are bottlenecks that need to be overcome to make carbon-based PSCs (C-PSCs) more attractive in practice. Herein, we report an effective method to enhance the interfacial charge transport of C-PSCs by introducing the CuSCN material into the device. Two types of CuSCN-assisted devices were studied in this work. One was based on the deposition of an ultrathin CuSCN layer between the perovskite absorber layer and the carbon cathode (PSK/CuSCN/C), and the other was by infiltrating CuSCN solution into the carbon film (PSK/C-CuSCN) by taking advantage of the macroporous structure of the carbon. We have found that the CuSCN incorporation by both methods can effectively address the hysteretic feature in planar C-PSCs. The origin for the hysteresis evolution was unraveled by the investigation of the energy alignment and the kinetics of interfacial charge transfer and hole trap-state density. The results have shown that both types of CuSCN-containing devices showed improved interfacial charge carrier extraction, suppressed carrier recombination, reduced trap-state density, and enhanced charge transport, leading to negligible hysteresis. Furthermore, the CuSCN-incorporated C-PSCs demonstrated enhanced device stability. The power conversion efficiency remained 98 and 91% of the initial performance (13.6 and 13.4%) for PSK/CuSCN/C and PSK/C-CuSCN, respectively, after being stored under a high humidity (75–85%) environment for 10 days. The devices also demonstrated extraordinary long-term stability with a negligible performance drop after being stored in air (relative humidity: 33–35%) for 90 days.

Carbon electrode-based planar PSCs demonstrated higher device performance and reduced hysteresis using a CuSCN based HTL owing to its favourable energy level alignment with the perovskite compared to conventional spiro-OMeTAD based HTL.