Metal-free chiral molecular ferroelectric photovoltaics

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2023-12, Vol.477, p.146805, Article 146805
• Main Authors: Jiao, Shulin, Jiang, Haidong, Fan, Changchun, Xu, Cuiping, Jiang, Junjie, Xu, Yanming, Tang, Zheng, Sun, Xiaofan, Ji, Peiqi, Yang, Xingming, Ye, Kongmeng, Xu, Libo, You, Qi, Chen, Shuang, Cai, Hong-Ling, Wu, Xiaoshan
• Format: Article
• Language: English
• Subjects: Chiral ferroelectric; Ferroelectric photovoltaics; Ferroelectric semiconductors; Metal-free ferroelectric
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2023.146805

[Display omitted] •A pair of novel metal-free chiral molecular ferroelectric semiconductors was prepared.•Construction of narrow band gap structures by introducing polyiodide anions.•Designing ferroelectrics with helical arrangement by chiral chemical means.•The initial application in photovoltaics is demonstrated. Ferroelectric semiconductors have gained significant attraction for designing photovoltaic devices. However, their wide bandgap results in poor absorption of visible light. Herein, we report a pair of chiral metal-free molecular ferroelectric semiconductors (1R,4R/1S,4S-C5H10NO)I3 (R/S-OABHI; (1R,4R/1S,4S-C5H10NO)+ = 1R,4R/1S,4S-2-oxa-5-azabicyclo[2.2.1]heptonium) with notable ferroelectricity (saturation polarization of ∼6.8 and 6.1 μC/cm2 for R-/S-OABHI, respectively). They demonstrate an appropriate photovoltaic bandgap of ∼ 1.41 and 1.39 eV for R-/S-OABHI, respectively, comparable to MAPbI3 (MA = methylammonium). Experiments and computational simulations reveal that the ferroelectricity of R/S-OABHI originates from their non-centrosymmetric crystal packing in a controllable helical manner, while the I3− contributes to band edges. Meanwhile, photovoltaic effect is firstly observed in the R-OABHI based solar cell with an open-circuit voltage of 0.581 V and a short-circuit current density of 1.734 mA/cm2. Overall, we establish a new approach for realizing metal-free ferroelectric photovoltaics, and it will pave the way for the exploration of multifunctional chiral molecular ferroelectrics.