Boosting internal quantum efficiency via ultrafast triplet transfer to 2H-MoTe2 film

Abstract

Organic systems often allow to create two triplet spin states (triplet excitons) by converting an initially excitedsinglet spin state (a singlet exciton). An ideally designed organic/inorganic heterostructure could reach the pho-tovoltaic energy harvest over the Shockley-Queisser (S-Q) limit because of the efficient conversion of triplet ex-citons into charge carriers. Here, we demonstrate the molybdenum ditelluride (MoTe2)/pentaceneheterostructure to boost the carrier density via efficient triplet transfer from pentacene to MoTe2 using ultrafasttransient absorption spectroscopy. We observe carrier multiplication by nearly four times by doubling carriers inMoTe2 via the inverse Auger process and subsequently doubling carriers via triplet extraction from pentacene.We also verify efficient energy conversion by doubling the photocurrent in the MoTe2/pentacene film. This putsa step forward to enhancing photovoltaic conversion efficiency beyond the S-Q limit in the organic/inorganicheterostructures.