Optimized organometal halide perovskite solar cell fabrication through control of nanoparticle crystal patterning

Abstract

The addition of Hydrogen Iodide to organometal halide perovskite precursor solution at 1% by volume leads to a 10 significant enhancement in average power conversion efficiency (PCE) in inverted solar cell devices, increasing from 7.7% 11 to 11.9% and 6.1% to 10.0% in spin-cast and spray-cast devices respectively. We directly attribute this improved device 12 performance to increased thin-film surface coverage coupled with higher optical density. X-ray diffraction studies also 13 reveal that the HI additive facilitates full conversion of the precursor material to the crystalline perovskite phase. From 14 solution studies, we relate these changes in device performance to the presence and distribution of precursor aggregates 15 that effectively pattern the formation of perovskite crystals during film formation. 16

In situ simultaneous photovoltaic and structural evolution of perovskite solar cells during film formation

“…1 we show a summary of the measurements performed on an IBC solar cell spin-coated with a precursor solution made of MAI : PbCl 2 (2.95 : 1 M) with HI additive (1%) in dimethylformamide (DMF), which is a recipe able to produce high performance solar cells in the ambient conditions employed here. 10,36 The perovskite-coated IBC solar cell (IBC130) was annealed at 88.2 1C (measured at the sample surface) under N 2 atmosphere to minimise X-ray beam damage. The as-coated film undergoes a three-stage evolution: (i) precursor phase conversion into perovskite phase, (ii) perovskite crystallization, (iii) perovskite degradation into lead iodide.…”

“…Addition of HI results in continuous perovskite films and more efficient solar cells compared to bare MAI:PbCl 2 . 10,36 The as-prepared solution was used for preparing the planar solar cells, however the IBC solar cells required a much thinner perovskite layer. For this reason, the solution was further diluted twice in DMF.…”

Spray-cast multilayer perovskite solar cells with an active-area of 1.5 cm2

“…The precursor perovskite films (2.95:1.00 MAI:PbCl 2 solution containing 1% (by volume) hydrogen iodide (HI) in DMF were then coated on the FTO/cTiO 2 /mTiO 2 surface under ambient lab conditions maintained at (20 ± 2)°C and (30 ± 5)% RH. Here, the role of the HI additive was to improve the solubility of PbCl 2 and increase the surface coverage of the final perovskite film 36 . This precursor was spray-cast using our previously-described methods used to fabricate inverted-architecture PSC devices 16 , 27 .…”

Degradation of inverted architecture CH3NH3PbI3‐xClx perovskite solar cells due to trapped moisture

“…Here, films were not encapsulated, but were stored in a dry environment (at a relative humidity of ~30%) to characterize the dominant degradation mechanisms. Typical data are presented in Figure , where we show X‐ray diffraction around the (110) perovskite and (001) PbI 2 reflections . Here, it can be seen that after approximately 2 weeks, the presence of PbI 2 is detected through the growth of a (001) scattering feature at an angle of 12.5°.…”