The effect of plasmonic enhancement on the two-photon absorption cross section of organic chromophores attached to polyelectrolyte-coated gold nanorods was investigated. The magnitudes of such enhancements were confirmed using single and two photon excitations of the chromophore molecules bound to polyelectrolyte-coated gold nanorods. By synthesizing two-, four-, six-, and eight-polyelectrolyte layer coated nanorods of a particular aspect ratio, the distance dependence of the evanescent electromagnetic field on molecular two-photon absorption was observed. Enhancements of 40-fold were observed for the chromophores nearest to the surface.

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This review is written to introduce infrared photon detectors based on solution-processable semiconductors. A new generation of solution-processable photon detectors have been reported in the past few decades based on colloidal quantum dots, two-dimensional materials, organics semiconductors, and perovskites. These materials offer sensitivity within the infrared spectral regions and the advantages of ease of fabrication at low temperature, tunable materials properties, mechanical flexibility, scalability to large areas, and compatibility with monolithic integration, rendering them as promising alternatives for infrared sensing when compared to vacuum-processed counterparts that require rigorous lattice matching during integration. This work focuses on infrared detection using disordered semiconductors so as to articulate how the inherent device physics and behaviors are different from conventional crystalline semiconductors. The performance of each material family is summarized in tables, and device designs unique to solution-processed materials, including narrowband photodetectors and pixel-less up-conversion imagers, are highlighted in application prototypes distinct from conventional infrared cameras. We share our perspectives in examining open challenges for the development of solution-processable infrared detectors and comment on recent research directions in our community to leverage the advantages of solutionprocessable materials and advance their implementation in next-generation infrared sensing and imaging applications.among many other areas. Commercially available IR detectors are predominantly based on vacuum-processed inorganic compound semiconductors, which are structurally rigid, brittle, and require fabrication via complex epitaxial growth and costly processes. A new generation of solution-processable semiconductors have been reported in the past few decades including colloidal quantum dots (CQDs) [1,8,9], organic semiconductors (OSCs) [4,7,10,11], perovskites [1,12,13], and two-dimensional (2D) materials [5,14]. These materials offer sensitivity within the IR spectral regions and the advantages of ease of fabrication

A time-resolved photoluminescence quenching approach is developed for determining the triplet exciton diffusion coefficient and diffusion length (D and L D , respectively) of phosphorescent conjugated polymers. This method is applied to a solid-state organometallic conjugated polymer with the structure [−Pt(PBu 3 ) 2 −CC−C 6 H 4 −CC−] n (where Bu = n-butyl and −C 6 H 4 − is 1,4-phenylene). The approach relies on analysis of the lifetime quenching of the polymer's phosphorescence by a series of three different quenchers that are dispersed into the polymer phase at varying concentration. The lifetime quenching data are analyzed by using a modified Stern−Volmer quenching expression to determine the diffusion-controlled quenching rate constant, k q , which is then related to the exciton diffusivity, D, and diffusion length, L D . The diffusion coefficients that are determined using the three quenchers are consistent, D ≈ 4 × 10 −6 cm 2 s −1 , and combined with the triplet exciton lifetime of the pristine polymer (τ = 1.05 μs) give an exciton diffusion length L D ≈ 22 nm. The results are compared to literature studies of singlet exciton diffusion in conjugated polymers and triplet exciton diffusion in molecular materials.