A Ferroelectric p–i–n Heterostructure for Highly Enhanced Short‐Circuit Current Density and Self‐Powered Photodetection

Abstract 2D‐layered materials and van der Waals heterostructures (vdWHs) have attracted intense interests in optoelectronic applications. However, the performance of photovoltaic effect based on vdWHs is still unsatisfactory, which is subjected to many factors, including settled small built‐in potentials and low light absorptions. Here, a pronounced photovoltaic effect is reported in MoTe 2 /(C 4 H 9 NH 3 ) 2 (CH 3 NH 3 ) 2 Pb 3 I 10 /α‐In 2 Se 3 ferroelectric p–i–n vdWHs. An all‐dry transfer method held in an inert environment is utilized to ensure a good materials’ stability and high interfacial quality. The short‐circuit current density can increase three orders to 38 mA cm −2 by introducing perovskite; hence, the device works as a sensitive self‐powered photodetector with a photo on/off ratio of 2.4 × 10 5 , a detectivity of 1.2 × 10 12 Jones, and response times of 730 µs/620 µs. Moreover, the short‐circuit current density increases more than 25 times by enhancing the built‐in potential through programming the ferroelectric polarization of α‐In 2 Se 3 . In total, short‐circuit current density as high as 468 mA cm −2 is reached, which is one‐to‐two orders higher than that of typical lateral vdWHs. This work demonstrates the potential of high‐performance optoelectronic devices based on ferroelectric van der Waals p–i–n heterostructures.