摘要
Singlet fission (SF) provides a viable mechanism to surpass the Shockley-Queisser efficiency limit in photovoltaic devices, where excitation energy plays a pivotal role in modulating the SF process. In this study, the SF dynamics are systematically characterized by measuring magneto-photoluminescence (MPL) under two distinct excitation wavelengths (403 and 440 nm) in a tetracene-based thin film. High-energy excitation (403 nm) yields a higher MPL intensity, indicating a higher degree of SF in the absence of an external magnetic field. These results suggest that excitation energy significantly modulates SF and influences the triplet-triplet 1(TT) pair separation. To confirm this, temperature-dependent MPL measurements reveal the activation energies of 53.36 and 68.61 meV, corresponding to the energy required for 1(TT) pair separation for 403 and 440 nm excitation, respectively. Moreover, the incident photon-to-current efficiency (IPCE) measurements of the tetracene-based photodiode exhibit a relatively high response in the 300-400 nm wavelength range, peaking at 380 nm. Notably, the integrated current density (J) within this spectral region contributes approximate to 31% to the total photocurrent. These results indicate the possibility of harvesting high-level excitation energy through SF in a tetracene-based photodiode and suggest the importance of 1(TT) pair separation in optimizing the SF-based photovoltaics.