Table 1. Calculated excitation energies, oscillator strengths, and molecular orbital (MO) compositions for the low-lying excited states of NP4C, folded NP4C, NPM and NPMC.

Compound	State	Excitation energy (eV)	Oscillator strength	MO composition
NP4C	S1	2.08	0.0000	H → L (94.7%)
	S2	2.09	0.0000	H-1 → L (93.9%)
	S3	3.56	0.5205	H-2 → L (94.0%)
Folded NP4C	S1	3.22	0.0451	H → L (85.4%)
	S2	3.29	0.0494	H-1 → L (75.7%)
	S3	3.42	0.3477	H-2 → L (72.3%)
NPM	S1	3.53	0.3860	H → L (94.1%)
NPMC	S1	3.34	0.0080	H → L (76.0%)
	S2	3.42	0.2781	H-1 → L (85.5%)