Bulk photovoltaic effect, characterized by an excitation-driven unbiased spontaneous photocurrent, has attracted substantial attention mainly due to its potential for harvesting solar energy. Here, we investigate the photovoltaic characteristics of organic molecular solids and focus on the association between the photocurrent and the crystal symmetry in the exemplary case of tetrathiafulvalene-p-chloranil. We perform comprehensive first-principles calculations, including direct evaluations of the excited-state current via real-time propagations of the time-dependent density functional theory. We find that the charge shifting in the low-temperature phase is mainly driven by the intrachain ferroelectricity, which gives rise to a photocurrent not only in the visible-light range but also near the band-edge infrared region. The shift current that is locked in the symmetry of the high-temperature phase can be released by introducing a potential asymmetry. We suggest that organic molecular solids can be exploited via appropriate engineering to lower the symmetry, aiming at room-temperature photovoltaics.

以激发驱动的无偏自发光电流为特征的块状光伏效应引起人们的广泛关注，这主要是由于其具有收集太阳能的潜力。在这里，我们研究有机分子固体的光伏特性，并集中在四硫富瓦烯-p的示例情况下，光电流与晶体对称性之间的关联-氯苯胺。我们执行全面的第一性原理计算，包括通过随时间变化的密度泛函理论的实时传播对激发态电流进行直接评估。我们发现，低温相中的电荷移动主要由链内铁电驱动，不仅在可见光范围内而且在带边缘红外区附近也会产生光电流。通过引入电位不对称性，可以释放锁定在高温相对称性中的移位电流。我们建议可以通过适当的工程利用有机分子固体来降低对称性，其目标是室温光伏。