Revealing Collaborative Effects of Binary Additives on Regulating Precursor Crystallization Toward Highly Efficient Perovskite Solar Cells

Abstract

Fabricating high-quality perovskite layers is essential for achieving high-performance solar cells. Considering the significant advancements made in additive engineering for optimizing perovskite crystallization using single additive, exploring the collaborative effect of dual additives on precursor for perovskite crystallization may be an effective way for further advancing device performance. Herein, a binary additives strategy is proposed, where phenylmethylammonium iodide (PMAI) and [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz) are introduced into the precursor. Compared with the precursor with no additives or a single additive (PMAI or 2PACz), the use of dual additives more effectively cleaves edge-shared Pb-I octahedra to expedite the transformation from PbI₂ to PbI₃⁻ complexes as prenucleation clusters and produces much larger colloidal particles with accelerated nucleation. Concurrently, the crystallization in both spin-coating and annealing processes is significantly retarded due to the stronger interaction between perovskite and binary additives. Benefiting from such rapid nucleation and slow crystallization, high-quality perovskite layer with larger-sized crystals and fewer defects is formed, resulting in mitigated microstrain, enhanced charge extraction, and suppressed nonradiative recombination. Consequently, the device derived from the use of dual additives could achieve an impressive efficiency of 26.05% (certified 25.49%) and retained 90% of its initial efficiency after 1200 h of maximum power point tracking.