Electrochemistry measurements. Cyclic Voltammetry (CV) and Differential pulse voltammetry (DPV) analysis was performed on an Electrochemical Analyzer potentiostat model 620E from CH Instruments at a sweep rate of 100 mV/s. Differential pulse voltammetry (DPV) was conducted with an increment potential of 0.004 V and a pulse amplitude, width, and period of 50 mV, 0.05, and 0.5 s, respectively. Samples were prepared in HPLC grade Acetonitrile (MeCN) solutions, which were degassed by sparging with MeCN-saturated nitrogen gas for 5 minutes prior to all measurements. All measurements were performed using 0.1 M tetra-n-butylammonium hexafluorophosphate, [n-Bu4N]PF6, in MeCN. An Ag/Ag + electrode was used as the reference electrode; a glassy carbon electrode was used as the working electrode and a platinum wire was used as the counter electrode. The redox potentials are reported relative to a saturated calomel electrode (SCE) with a ferrocene/ferrocenium (Fc/Fc + ) redox couple as the internal standard (0.38 V vs SCE). The HOMO and LUMO energy levels were determined using the relation EHOMO/LUMO = -(E ox/red + 4.8) eV, where E ox and E red are the anodic and cathodic DPV peak potentials of the first oxidation and reduction peaks, respectively. Photophysical measurements. Solutions were prepared in HPLC-grade oxygen-free toluene at a concentration of 0.05 mg/mL, equal to 1.0 × 10 -4 M, 7.15 × 10 -5 M and 5.52 × 10 -5 M for 4TABN1, 5TABN2 and 6TABN3, respectively. Neat and doped films were prepared from a 2.5 mg/mL oxygen-free chloroform solution by spin-coating at 2000 RPM. For the doped films, 1,3,10 or 30 wt% of guest had been dispersed into DPEPO. For PLQY measurements, drop-cast films were made at 60 °C from a solution with the oxygen-free chloroform. Absorption measurements were carried out at room temperature using a Cary 5000 UV-Vis-NIR absorption spectrophotometer. Steady-state photoluminescence spectra at RT and 77 K, PL emission in the ms range at 77 K as well as PLQY measurements at RT were obtained using the Jasco FP-8600 spectrofluorometer for different excitations (as specified in figure captions). The thin film PLQY were measured in a N2 filled integrating sphere. For measurements at 77 K, the film or cuvette was immersed in liquid nitrogen. The time-resolved photoluminescence measurements were obtained using an iCCD camera and exponentially increasing delay and gating times, where the gating time is kept lower by a factor of 10 compared to the delay time. Samples were excited at 355 nm by a q-switched laser from QS Lasers (MPL15100-DP). Emission from the samples was focused onto a spectrograph (Oriel MS257) and detected on a gated iCCD camera (iStar A-DH334T-18F-03). The measurements were recorded under vacuum or in a He filled atmosphere.