Fig. 1. Schematic presentation of the analyzed crystal structures: pentacene and tetracene (sketch in color) vs picene and chrysene (gray-scale sketch). Each set of lattice vectors {a, −a}, {b, −b} and {a+b2,−a+b2,−a+b2,−−a+b2} corresponds to a pair of exchange integrals (see text).

Fig. 2. Exciton dispersion in pentacene along three different directions in reciprocal lattice at T = 20 K. Experimental data are taken from Ref. [12]. Theoretical curves are obtained for Δ = 1.915 eV, I1Ax=3.2 meV, I2Ax=2.2 meV, I3Ax=38.2 meV.

Fig. 3. Exciton dispersion in pentacene along four different directions in reciprocal lattice at T = 300 K. Experimental data are taken from Ref. [10]. Theoretical curves are obtained for the exchange integral set from Fig. 2 and the gap value Δ = 1.83 eV.

Fig. 4. Exciton dispersion in tetracene along two different directions in reciprocal lattice. Experimental data at T = 20 K are taken from Ref. [14]. Theoretical curves are obtained for Δ = 2.405 eV, I1Ax=5.7 meV, I2Ax=0.4 meV, I3Ax=19.8 meV.

Fig. 5. The 3D plot of exciton dispersion in pentacene at T = 20 K. Parameter set is the same as in Fig. 2.

Fig. 6. Exciton dispersion in picene along three different directions in reciprocal lattice. Experimental data at T = 20 K are taken from Ref. [15]. Theoretical curves are obtained for Δ = 3.249 eV, I1Ax=2.8 meV, I2Ax=2 meV, I3Ax=2.8 meV.

Fig. 7. Exciton dispersion in chrysene along three different directions in reciprocal lattice. Experimental data at T = 20 K are taken from Ref. [15]. Theoretical curves are obtained for Δ = 3.4 eV, I1Ax=2.8 meV, I2Ax=2 meV, I3Ax=2.8 meV.

Fig. 8. The 3D plot of exciton dispersion in picene, obtained with the parameters from Fig. 6.