Transition-metal dichalcogenide heterostructure solar cells: A numerical study

We evaluate the tunneling short-circuit current density $J_{TU}$ in a $p$-$i$-$n$ solar cell in which the transition metal dichalcogenide heterostructure (MoS$_2$/WS$_2$ superlattice) is embedded in the intrinsic $i$ region. The effects of varying well and barrier widths, Fermi energy levels and number of quantum wells in the $i$ region on $J_{TU}$ are examined. A similar analysis is performed for the thermionic current $J_{TH}$ that arises due to the escape and recapture of charge carriers between adjacent potential wells in the $i$-region. The interplay between $J_{TU}$ and $J_{TH}$ in the temperature range (300 K - 330 K) is examined. The thermionic current is seen to exceed the tunneling current considerably at temperatures beyond 310 K, a desirable attribute in heterostructure solar cells. This work demonstrates the versatility of monolayer transition metal dichalcogenides when utilized as fabrication materials for van der Waals heterostructure solar cells.