Realizing Near‐Infrared Laser Dyes through a Shift in Excited‐State Absorption

Abstract

The development of near‐infrared (NIR) light sources has attracted much interest due to their attractive applications, such as biosensing and light detection and ranging (LiDAR). In particular, organic semiconductor laser diodes with NIR emission are emerging as a next generation technology. However, organic NIR emitters have generally suffered from a low quantum yield, which has resulted in only a few examples of organic solid‐state NIR lasers. In this study, the authors demonstrate a highly efficient NIR emitter based on a boron difluoride curcuminoid structure, which shows a high photoluminescence (PL) quantum yield (ΦPL) at >700 nm and a high fluorescence radiative rate constant in a solid‐state film. Amplified spontaneous emission and lasing occurs at >800 nm with very low thresholds. The large redshift of the stimulated emission is attributed to the transition from the lowest excited state to the different vibrational levels of the ground state owing to the overlap between the emission and the singlet–singlet excited‐state absorption.

Gain Bandwidth Engineering in Polymer Blends for Full‐Color‐Tunable Lasers

“…The existence of re‐absorption, singlet‐singlet excited state absorption, charge absorption, and triplet‐triplet excited state absorption is known to affect the light amplification properties. [ 2,18,19 ] Therefore, the effective σ em (λ) (σ em, eff (λ)) is defined by the following equation (Equation ()): [ 59,60 ] where σ abs (λ) is the absorption cross‐section of the ground‐state species, σ S‐S (λ) is absorption cross‐section of the singlet‐singlet excited‐state species, σ charge (λ) is charge absorption cross‐section, and σ T‐T (λ) is triplet‐triplet excited‐state absorption cross‐section. Due to the negligible overlap between host PIA and effective gain regions from TA measurements, σ S‐S (λ), σ charge (λ) and σ T‐T (λ) at each selected emission wavelength are almost zero in the BEHP‐PPV:MEH‐PPV blend system.…”

“…The existence of re-absorption, singlet-singlet excited state absorption, charge absorption, and triplet-triplet excited state absorption is known to affect the light amplification properties. [2,18,19] Therefore, the effective σ em (λ) (σ em, eff (λ)) is defined by the following equation (Equation ( 6)): [59,60] em, eff em abs SS c harge TT…”

Precise synthesis of multilevel branched organic microwires for optical signal processing in the near infrared region

“…We combined two DHMAC molecules to elongate the π-conjugation length, which leads to a narrowing of the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energy gap and results in further red shift emission (Fig. 1b, c) [54,55]. A larger π-conjugated system can strengthen the intermolecular π-π interaction, which is helpful for the formation of uniaxially oriented molecular crystals [56].…”

Effect of the electron donating group on the excited-state electronic nature and epsilon-near-zero properties of curcuminoid-borondifluoride dyes

“…Within the examples reported here, we showed that the polymethine character can be correlated to some extend to the presence and the broadening of ENZ spectral region in pristine thin lm. The dyes with CT character work efficiently for emissive organic electronics applications 21,23,24 while not showing ENZ properties. On the other hand, the polymethine character in Curc dyes is associated with characteristics related to ENZ materials.…”