Self-assembly of excitonic nanostructures from excess cationic MAI:PbCl2 perovskite solutions.

Perovskite solar cells utilising NiO and TiO2 charge-extraction layers, deposited via high-speed, low substrate-temperature reactive electron-beam evaporation, achieve 15.8% PCE.

An encapsulation system comprising of a UV-curable epoxy, a solution processed polymer interlayer, and a glass cover-slip, is used to increase the stability of methylammonium lead triiodide (CH3NH3PbI3) perovskite planar inverted architecture photovoltaic (PV) devices. It is found this encapsulation system acts as an efficient barrier to extrinsic degradation processes (ingress of moisture and oxygen), and that the polymer acts as a barrier that protects the PV device from the epoxy before it is fully cured. This results in devices that maintain 80% of their initial power conversion efficiency after 1000 h of AM1.5 irradiation. Such devices are used as a benchmark and are compared with devices having initially enhanced efficiency as a result of a solvent annealing process. It is found that such solvent-annealed devices undergo enhanced burn-in and have a reduced long-term efficiency, a result demonstrating that initially enhanced device efficiency does not necessarily result in long-term stability.

We explore degradation pathways within encapsulated CH3NH3PbI3-xClx perovskite devices based on the inverted architecture: ITO/PEDOT:PSS/CH3NH3PbI3-xClx/PC70BM/LiF/Al. Devices were subjected to more than 670 h of continuous illumination approximating AM1.5, with a Ts80 lifetime of (280 +/- 20) hours determined. Devices stored in the dark underwent a similar drop in efficiency over the same time-period. Using external quantum efficiency, time-resolved photoluminescence, X-ray diffraction, scanning electron microscopy and laser beam induced current mapping, we attribute the primary cause of degradation to reactions with residual moisture trapped in the device, resulting in the decomposition of the perovskite.

The addition of hydrogen iodide to organometal halide perovskite precursor solution at 1% by volume leads to a significant enhancement in average power conversion efficiency (PCE) in inverted solar cell devices.

The water soluble conjugated polyelectrolyte was synthesised by Suzuki cross coupling and increased the power conversion efficiency by improving hole charge transfer from active layer into the hole transporting layer.