(407c) Temperature Dependent Photovoltaic Characteristics of Graphene/h-BN/Si Solar Cell
AIChE Annual Meeting
2019
2019 AIChE Annual Meeting
Nanoscale Science and Engineering Forum
Graphene 2-D Materials: Synthesis, Functions and Applications II
Tuesday, November 12, 2019 - 4:10pm to 4:30pm
Graphene-on-semiconductor heterojunction solar cell is an emerging class of photovoltaics with potential for efficient and reliable energy conversion systems. The interfaces between graphene and lightly-doped semiconductor play a key role in charge-carrier separation and recombination dynamics. Owing to the low Schottky barrier height-induced interfacial charge carrier recombination, the graphene-on-silicon (Si) heterojunction solar cells suffer from instability in power conversion efficiency over time. Therefore, it is critical to engineer the interface to enhance the barrier height by interfacing a chemically-stable, insulating, and atomically-thin layer. Further, the temperature dependent photovoltaic characteristics of such stacked architectures are unknown. Here, we have introduced hexagonal boron nitride (h-BN) as a tunneling interlayer in graphene-on-Si heterojunction solar cells, which enables the passivation of the chemical dangling bonds on the Si surface. The effect of temperature on the performance of graphene/h-BN/Si PV cell is also examined. Thin films of h-BN are directly synthesized on lightly-doped Si surface via a bottom-up chemical-surface-adsorption strategy followed by the transfer of a graphene monolayer. The 2D layer-on-2D layer-on-3D bulk semiconductor nanoarchitecture of graphene/h-BN/Si forms a metal-insulator-semiconductor (MIS)-type junction, where the h-BN acts as an electron-blocking layer to avoid interfacial charge carrier recombination. A 4-fold increase in open-circuit voltage (VOC) is found for graphene/h-BN/Si heterojunction cell (0.52 V) in contrast to the graphene/Si cell (0.13 V), which is due to the increase in the Schottky barrier height and hence built-in electric potential. Interestingly, the VOC linearly decreases by only ~4% with every 10 K increase in temperature. Durability studies indicate that the VOC of graphene/h-BN/Si solar cell is practically unaffected for 1-year. This work will lead to an evolution of new 2D/2D/3D nanoarchitectures for mechanically-robust, high performance, and durable optoelectronic functionalities.