Ideal carrier multiplication in monolayer MoSe2
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Carrier multiplication (CM), the process of generating multiple charge carriers from a single photon, offers an opportunity to exceed the Shockley-Queisser limit for solar cell efficiency. However, realizing significant efficiency improvements through CM in traditional semiconductors has proven challenging, necessitating fine-tuning of material properties. In this study, we utilize ultrafast transient absorption spectroscopy to demonstrate that monolayer MoSe 2 can achieve the theoretical maximum CM efficiency allowed by energy-momentum conservation laws. By resolving the spatiotemporal dynamics of hot carriers and employing first-principles calculations, we identify the cornerstone of optimal CM in MoSe 2 : superior hot carrier dynamics characterized by effective suppression of energy loss via carrier-lattice scattering, and the availability of abundant CM pathways facilitated by 2E g band nesting. Our findings position monolayer MoSe 2 as an exceptional candidate for advanced optoelectronic applications and as a pivotal platform for exploring quantum hot carrier dynamics.
