Photon recycling in organic semiconductor films using plasmonic metasurfaces

Abstract

Photon recycling (PR) is a type of iterative self-absorption and re-emission by semiconductors. It plays an important but often-overlooked role in the performance of semiconductor optoelectronic devices. Additionally, it has not previously been investigated in the case of organic semiconductors, despite their propensity to exhibit for self-absorption. In this work, we study PR in thin films of three different organic semiconducting polymers on a variety of different surfaces to investigate the role of PR on the emission from the films. We show that PR is strongly affected by the substrate surface type and the morphology of the semiconductor. Silver grating-based metasurfaces and symmetric dielectric waveguides increase PR by up to a factor of 1.72 in all organic thin films compared to those on planar silver surfaces. However, polymer films with significant surface roughness do not show strong PR effects due to reduced guiding of emission in the plane of the film. Additionally, the luminescence quantum yield of all polymers is enhanced by both silver nanoparticle- and grating-based metasurfaces (by up to factors of 1.7 and 1.5, respectively) compared to the planar silver surfaces. This is attributed to the Purcell effect and improved extraction of emission coupled to surface plasmon polariton (SPP) modes. This study demonstrates that PR can be achieved in organic semiconductors, and it is strongest for surfaces and structures that promote both high quantum yield and in-plane waveguiding at the semiconductor emission wavelength.