The First Ring Enlargement Induced Large Piezoelectric Response in a Polycrystalline Molecular Ferroelectric oleh Yong Ai, Peng‐Fei Li, Xiao‐Gang Chen, Hui‐Peng Lv, Yan‐Ran Weng, Yu Shi, Feng Zhou, Ren‐Gen Xiong, Wei‐Qiang Liao