Polyacetylene derivatives in perovskite solar cells: from defect passivation to moisture endurance

The last decade has witnessed the exploration of exceptional optoelectronic and photovoltaic properties of perovskite solar cells (PSCs) at the laboratory scale. Unfortunately, their sensitivity to moisture causes bulk degradation, hindering the commercialization of PSC devices. Despite the numerous strategies that have been developed to date in this field, effective passivation against moisture remains highly challenging. Here, we report a novel approach based on the incorporation of polyacetylene derivatives into the perovskite active layer to yield perovskite films with larger grains, lower defect density, and excellent robustness with respect to moisture. Moreover, it is revealed that the reduced trap-state density of these films is most likely due to the efficient coordination between the carboxylate moieties in the polymer and the undercoordinated Pb2+ in the perovskite. Upon adopting the polymer-doped perovskite as an active layer in inverted planar heterojunction PSCs with all-inorganic charge extraction layers, the power conversion efficiency (PCE) is improved to 20.41%, which is the highest value reported to date for this type of PSC to the best of our knowledge. Most importantly, the optimized device retained 90% of its initial PCE after aging in ambient air for 60 days due to its dual mechanism of moisture resistance. This work highlights an approach for developing high-performance PSCs with improved moisture stability and paves the way for their potential commercialization.