Unveiling the Nanoparticle‐Seeded Catalytic Nucleation Kinetics of Perovskite Solar Cells by Time‐Resolved GIXS

• Published in: Advanced functional materials Vol. 29; no. 36
• Main Authors: Lin, Chung‐Yao, Li, Shao‐Sian, Chang, Je‐Wei, Chia, Hao‐Chung, Hsiao, Yu‐Yun, Su, Chun‐Jen, Lian, Bing‐Jun, Wen, Cheng‐Yen, Huang, Shao‐Ku, Wu, Wei‐Ru, Wang, Di‐Yan, Su, An‐Chung, Chen, Chun‐Wei, Jeng, U‐Ser
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.09.2019
• Subjects: Alignment; Catalysis; catalytic additives; Conversion; Crystal lattices; Crystal structure; Crystals; Cubic lattice; grazing‐incidence X‐ray scattering; heterogeneous interface; Lead sulfides; Materials science; Morphology; Nanocrystals; Nanoparticles; Nucleation; organo‐lead trihalide perovskite; PbS nanocrystals; Perovskites; Photovoltaic cells; Pinholes; Reaction kinetics; Solar cells; Thermal stability; Thin films
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201902582

Recently, a new seeding growth approach for perovskite thin films is reported to significantly enhance the device performance of perovskite solar cells. This work unveils the intermediate structures and the corresponding growth kinetics during conversion to perovskite crystal thin films assisted by seeding PbS nanocrystals (NCs), using time‐resolved grazing‐incidence X‐ray scattering. Through analyses of time‐resolved crystal formation kinetics obtained from synchrotron X‐rays with a fast subsecond probing time resolution, an important “catalytic” role of the seed‐like PbS NCs is clearly elucidated. The perovskite precursor‐capped PbS NCs are found to not only accelerate the nucleation of a highly oriented intermediate phase, but also catalyze the conversion of the intermediate phase into perovskite crystals with a reduced activation energy Ea = 47 (±5) kJ mol−1, compared to 145 (±38) kJ mol−1 for the pristine perovskite thin film. The reduced Ea is attributed to a designated crystal lattice alignment of the perovskite nanocrystals with perovskite cubic crystals; the pivotal heterointerface alignment of the perovskite crystals coordinated by the Pb NCs leads to an improved film surface morphology with less pinholes and enhanced crystal texture and thermal stability. These together contribute to the significantly improved photovoltaic performance of the corresponding devices. Time‐resolved grazing‐incidence X‐ray scattering reveals cascade effects of PbS nanocrystals seeded in perovskite thin films. During annealing, PbS nanocrystals accelerate the nucleation of a highly oriented intermediate phase L1 through capped organic perovskite precursors, and subsequently catalyze the L1‐to‐perovskite conversion via lattice anchoring alignment with the cubic lattice of the perovskite, leading to improved crystal grain connectivity, texture, and thermal stability.