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.

铁电半导体对于光伏器件的设计具有巨大的吸引力。然而，它们的宽带隙导致可见光吸收较差。在此，我们报道了一对手性无金属分子铁电半导体 (1 R ,4 R /1 S ,4 S - C ₅ H ₁₀ NO)I ₃ ( R/S-OABHI ; (1 R ,4 R /1 S ,4 S - C ₅ H ₁₀ NO) ⁺ = 1 R ,4 R /1 S ,4 S -2-氧杂-5-氮杂双环[2.2.1]庚鎓)，具有显着的铁电性（饱和极化为 ∼6.8 和 6.1）R-/S-OABHI分别为μC/cm ²）。他们证明了R-/S-OABHI的适当光伏带隙分别为 ∼ 1.41 和 1.39 eV ，与 MAPbI ₃（MA = 甲基铵）相当。实验和计算模拟表明， R / S-OABHI的铁电性源于其以可控螺旋方式的非中心对称晶体堆积，而 I ₃ ^-则有助于带边。同时，在R-OABHI基太阳能电池中首次观察到光伏效应，开路电压为0.581 V，短路电流密度为1.734 mA/cm ²。总的来说，我们建立了一种实现无金属铁电光伏的新方法，它将为多功能手性分子铁电体的探索铺平道路。