Molecular engineering mechanism of organic photoactive layer by alkyl chains, 4-butoxyphenyl and cyanogroup

The three organic dye molecules (JY31, JY32 and JY33) were applied to the photoactive layer in solar cells. Photophysical and photochemical characteristic have been investigated with natural bond orbital (NBO), frontier molecular orbital, ionization potentials, electron affinities, absorption properties, reorganization energies, static first hyperpolarizability, emission characteristics, IR spectra, charge density difference; the influence of alkyl chains and 4-butoxyphenyl on properties were revealed; Subsequently, three new molecules JY33-1, JY33-2 and JY33-3 were designed by inserting the electron withdrawing group –CN into the acceptor part of JY33 in order to understand molecular engineering mechanism. The results show that the three original molecules have relatively high molar extinction coefficients, and the molecule of JY33 with a 4-butoxyphenyl group enables a bathochromic shift in absorption spectrum and is beneficial to improve the hole transport, injection capacity and ICT properties as well as better energy levels matching. The current study provides an effective channel for manipulating performance in materials design of solar cells.