Molybdenum trioxide (MoOX, X < 3), with a large work function, can induce upward band bending in crystalline silicon (c‐Si) when constructing a heterojunction, which makes it an attractive candidate for hole‐selective contact in c‐Si solar cells. Herein, the passivation property and hole selectivity of MoOX thin films are investigated on p‐type c‐Si wafers using MoOX/aluminum (Al) as rear contacts. To elevate the performance from the aspect of light management, silver (Ag) and copper (Cu) are further used as back electrodes instead of Al. Solar cells with Ag electrodes deliver the best performance with a power conversion efficiency of 18.74%, followed by Cu (17.61%) and Al (16.36%) electrodes, attributing to the better reflectivity of Ag and Cu. It is also noted that solar cells with MoOX/Ag and MoOX/Cu contacts show significant degradation under room temperature storage. The interfacial evolutions are then carefully studied as a function of elevated temperature that accelerate the thermodynamic process. The degradation mechanism involves redox reaction and metal diffusion at the MoOX/metal interfaces. This work points out the importance of selecting the adjacent layers of MoOX and regulating the interfaces to stabilize the MoOX‐based c‐Si solar cells.

Molybdenum oxide (MoO X , X < 3) has been successfully demonstrated as an efficient passivating hole-selective contact in crystalline Si (c-Si) heterojunction solar cells because of its large bandgap (∼3.2 eV) and work function (∼6.9 eV). However, the severe performance degradation coming from the instability of the MoO X and its interfaces has not been well addressed. In this work, we started with a c-Si(p)/MoO X heterojunction solar cell that yielded a power conversion efficiency (PCE) of 15.86%, in which the MoO X film was synthesized by industry-compatible atomic layer deposition (ALD). The initial PCE dropped to 10.20% after 2 days because of severe migration of O and Ag at the MoO X /Ag interface. We solved this by the insertion of a CrO X layer between the MoO X layer and the Ag electrode. The solar cell was found to be stable for more than 8 months in air because of the suppression of interface degradation. Our work demonstrates an effective way of improving the stability of silicon solar cells with transition metal oxide carrier selective contacts.

As the architecture of choice for future artificial-intelligent systems, the ideas of in-memory-and in-sensor-computing paradigms based on nonvon-Neumann architecture possess broad application prospects such as neuromorphic and sensor-memory-processor fusion systems. At the same time, these promising applications put diversified and strict requirements on the device performances, such as fast response to external signals, robust data security, and 3D integration potential. In this work, Au@VO 2 IR photodetectors and Ti/Au/VO 2 /Ti/Au threshold switching selectors are constructed, where the VO 2 thin films are realized by magnetron sputtering and water-vapor assisted post-annealing. Fast IR response is achieved in Au@ VO 2 photodetectors through a surface plasmon resonance-assisted metalinsulator transition. Furthermore, electroforming-free, tunable threshold voltage, steep switching slope, and selectivity of more than two orders of magnitude are observed in Ti/Au/VO 2 /Ti/Au threshold switching selector. Combining the functionalities of photodetection and selector, a VO 2 -based optical convolution engine demonstrates accurate and secure image-processing capability. These VO 2 -based devices are demonstrated as promising candidates for novel non-volatile memory, neuromorphic computing and sensor-memory-processor fusion applications.