Exciton nonlinearities and optical gain in colloidal CdSe/CdS dot/rod nanocrystals

SABA, MICHELE;Marceddu M;QUOCHI, FRANCESCO;Minniberger S;Roither J;Gocalinska A;Kovalenko MV;Talapin DV;Heiss W;MURA, ANTONIO ANDREA;BONGIOVANNI, GIOVANNI LUIGI CARLO

2010-01-01

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Abstract

We characterized the optical nonlinearities of CdSe nanocrystals surrounded by rod-like CdS shells with ultrafast measurements of time-resolved photoluminescence. We measured the exciton-exciton interaction to be, depending on structure details, attractive or repulsive, by as much as 31 meV, due to the unique band alignment in the CdSe/CdS. This feature makes CdSe/CdS dot/rods promising gain media for solution-processable lasers, as it appears combined with 80% photoluminescence quantum yield, narrow size and shape distributions and the antenna effect of the CdS rod shell enhancing optical absorption by more than a factor 50 with respect to bare dots. © 2010 Materials Research Society.