Millimeter wave (mmwave) based small cell base stations (SCBSs) in 5G standard proposed by 3GPP are expected to support increased data rates and capacity of the network at the expense of increased energy consumption. Dynamic time division duplexing (TDD) has also been proposed in 5G to further improve the throughput of these SCBSs by choosing their individual TDD time fractions. These mmwave based SCBSs are expected to coexist along with microwave based macro base stations (MBSs). Hence, downlink/uplink decoupling (DUDe) has been proposed by 3GPP to compensate for the transmit power imbalance between MBSs and SCBSs. In this work, the joint problem of energy efficiency (achieved through SCBS sleeping) and resource allocation for dynamic TDD with DUDe is formulated as an optimization problem in presence of a generalized a-fair scheduler. The tradeoff between throughput and energy efficiency is analyzed for static and dynamic TDD schemes, with and without DUDe. Further, we show a throughput gain of 28.4% with marginal or no loss in energy efficiency for a dynamic TDD system with DUDe as compared to a static TDD system. © 2020 IEEE.