Singlet Sensitization of a BODIPY Rotor Triggered by Marriage with Perovskite Nanocrystals

Abstract

Surface chemistry and quantum confinement in nanocrystals (NCs) can modulate the energy transfer efficiency between lead halide perovskite (LHP) NCs and acceptor molecules in hybrid assemblies. It is demonstrated here that colloidal CsPbBr 3 NCs capped with the oleic acid/oleylamine ligand pair act as a good singlet sensitizer of meso-(4-carboxyphenyl) BODIPY dye (C-BPY). The energy transfer efficiency of ≈85% at 1 × 10 −6 m is consistent with the strong binding of the BODIPY to the NC surface via the carboxylate group, as is evidenced by nuclear magnetic resonance (NMR) and Fourier-transform infrared (FTIR) spectroscopies. A thorough analysis suggests a Förster resonance energy transfer (FRET) mechanism from the perovskite to the acceptor dye. These results provide a better understanding of the underlying interaction in perovskite−organic chromophore nanohybrids and can be employed in the design of novel harvesting assemblies.

Unraveling the Luminescence Quenching Mechanism in Strong and Weak Quantum-Confined CsPbBr3 Triggered by Triarylamine-Based Hole Transport Layers

“…A common feature of a larger dynamic quenching constant ( K D ) than the static quenching constant ( K S ) confirms the dominance of dynamic quenching over static in both NPLs and NCs when treated with TFB in the concentration range of 0.030–0.155 μM. We note that the calculated k q values are in the order of 10 15 [M –1 S –1 ] and are much higher than the typical diffusion-induced bimolecular quenching constant ( k diff = 10 10 [M –1 S –1 ]). , The k q values larger than this limit suggest the presence of surface binding interactions between NPLs/NCs and TFB and rule out purely diffusion-mediated PL quenching. PL quenching by charge transfer or energy transfer is another possibility that can occur at the same time scales, leading to dynamic quenching. , Overall, in the low concentration range of 0.030–0.155 μM, the steady-state and time-resolved Stern–Volmer plots revealed that the quenching is dominated by dynamic interactions between NPLs/NCs and TFB that are leading to a nonradiative charge transfer/trapping mechanism …”

“…There have been numerous reports on energy or electron transfer from perovskites to chromophores in the literature. − Generally, if such transfer occurs, the emission intensity of one compound (donor) decreases, the other (acceptor) increases, and corresponding changes will be reflected in their TRPL profile. In the current case, since the emission of TFB strongly overlaps with the excitonic absorption peak of NPLs, there is a possibility of energy transfer from TFB to NPLs.…”

“…Corresponding collisional constant k q can be derived from the τ 0 /τ vs the concentration of TFB plots. It is noteworthy that, unlike the steady-state Stern–Volmer plots, the time-resolved Stern–Volmer plots , show a linear relation with the concentration of the TFB when fitted with eq τ 0 / τ = 1 + K D [ Q ] = 1 + k q τ 0 [ Q ] where τ 0 corresponds to the PL lifetime of NPLs/NCs in the absence of TFB while τ is the lifetime of NPLs/NCs emission in the presence of the TFB, K D is the dynamic quenching constant, and k q is the bimolecular quenching rate constant. Such a linear dependence or the decreasing trend in the lifetime values (Table S1) at low concentrations of the TFB (0.030–0.155 μM) in both NPLs and NCs is an indication of the presence of a dynamic quenching process in addition to static quenching. , The values of K D obtained for NPLs and NCs as the fit parameters for τ 0 /τ vs [TFB] in Figure a,b are used to extract the contribution of the static quenching process using a modified Stern–Volmer equation (eq ).…”

“…The transfer from NPL to TFB is also not possible, considering the minimal overlap in the emission of NPL and absorption of TFB. Recently, several reports elucidated the energy transfer from perovskites to triplet states of chromophores. − To verify if such transfer is responsible for the luminescence quenching in NPLs, we employed weakly confined (average size = ∼12 ± 3 nm), narrow band gap, green-emitting CsPbBr 3 NCs with TFB, whose VB is expected to be below triplet state (∼2.2 eV) of TFB . In addition, the green NCs exhibit no spectral overlap with the TFB.…”

Dissimilar-at-boron N-BODIPYs: from light-harvesting multichromophoric arrays to CPL-bright chiral-at-boron BODIPYs

“…The post-functionalization versatility of the outstanding BODIPY (boron dipyrromethene) dyes is virtually ideal for achieving this goal, 7,8 including the generation of bright CPL. 9,10 Nevertheless, easily endowing photophysically-optimized BODIPYs with the additional properties required for a specific application is still challenging.…”