SummaryThe static PN junction is the foundation of integrated circuits. Herein, we pioneer a high current density generation by mechanically moving N-type semiconductor over P-type semiconductor, named as the dynamic PN junction. The establishment and destruction of the depletion layer causes the redistribution and rebounding of diffusing carriers by the built-in field, similar to a capacitive charge/discharge process of PN junction capacitance during the movement. Through inserting dielectric layer at the interface of the dynamic PN junction, output voltage can be improved and designed numerically according to the energy level difference between the valence band of semiconductor and conduction band of dielectric layer. Especially, the dynamic MoS2/AlN/Si generator with open-circuit voltage of 5.1 V, short-circuit current density of 112.0 A/m2, power density of 130.0 W/m2, and power-conversion efficiency of 32.5% has been achieved, which can light up light-emitting diode timely and directly. This generator can continuously work for 1 h, demonstrating its great potential applications.

A light-and mechanical-energy co-harvesting generator based on a dynamic metal/perovskite Schottky junction with output current density of 41.1 A/m 2 is reported, which reveals a nonlinear photo-enhanced effect related to the nonlinear interaction between the mechanical energy-induced bound back carriers and photo-generated carriers in dynamic metal/perovskite Schottky junction. Without obvious degradation when being bent 120 , the flexible Al/perovskite generator is promising for utilization as a flexible and portable power source.

Nowadays, many different kinds of novel generators have been introduced to convert nature power into electrical power, such as mechanical energy, [1,2] hydraulic energy, [3] solar energy, [4,5] thermal energy, [6] etc. These generators all possess an electric field to output power, however, the large

Static heterojunction-based electronic devices have been widely applied because carrier dynamic processes between semiconductors can be designed through band gap engineering. Herein, we demonstrate a tunable direct-current generator based on the dynamic heterojunction, whose mechanism is based on breaking the symmetry of drift and diffusion currents and rebounding hot carrier transport in dynamic heterojunctions. Furthermore, the output voltage can be delicately adjusted and enhanced with the interface energy level engineering of inserting dielectric layers. Under the ultrahigh interface electric field, hot electrons will still transfer across the interface through the tunneling and hopping effect. In particular, the intrinsic anisotropy of black phosphorus arising from the lattice structure produces extraordinary electronic, transport, and mechanical properties exploited in our dynamic heterojunction generator. Herein, the voltage of 6.1 V, current density of 124.0 A/m2, power density of 201.0 W/m2, and energy-conversion efficiency of 31.4% have been achieved based on the dynamic black phosphorus/AlN/Si heterojunction, which can be used to directly and synchronously light up light-emitting diodes. This direct-current generator has the potential to convert ubiquitous mechanical energy into electric energy and is a promising candidate for novel portable and miniaturized power sources in the in situ energy acquisition field.

Searching for light and miniaturized functional device structures for sustainable energy gathering from the environment is the focus of energy society with the development of the internet of things. The proposal of a dynamic heterojunction-based direct current generator builds up new platforms for developing in situ energy. However, the requirement of different semiconductors in dynamic heterojunction is too complex to wide applications, generating energy loss for crystal structure mismatch. Herein, dynamic homojunction generators are explored, with the same semiconductor and majority carrier type. Systematic experiments reveal that the majority of carrier directional separation originates from the breaking symmetry between carrier distribution, leading to the rebounding effect of carriers by the interfacial electric field. Strikingly, NN Si homojunction with different Fermi levels can also output the electricity with higher current density than PP/PN homojunction, attributing to higher carrier mobility. The current density is as high as 214.0 A/m2, and internal impedance is as low as 3.6 kΩ, matching well with the impedance of electron components. Furthermore, the N-i-N structure is explored, whose output voltage can be further improved to 1.3 V in the case of the N-Si/Al2O3/N-Si structure, attributing to the enhanced interfacial barrier. This approach provides a simple and feasible way of converting low-frequency disordered mechanical motion into electricity.