Observation of shift current in 2D hybrid perovskites

2D hybrid perovskites have shown enormous potential for optoelectronic applications. The unique organic-inorganic hybrid composition provides the flexibility to tune the crystal structures deliberately. Not only the physical properties can be optimized, the crystal symmetry can also be manipulated. In this work, we observed spontaneous photovoltages in (PEA)2PbI4, indicating that this particular type of 2D perovskite is noncentrosymmetric. Provided the significance of inversion symmetry breaking to novel optical and electronic functionalities, our discovery can advances this field by offering a new class of symmetry-breaking crystals with a vast chemical space.