Efficient planar organic solar cells with the high near-infrared response

Abstract

Efficient planar organic solar cells extending the response into the near-infrared (NIR) were fabricated using the highly ordered Titanyl phthalocyanines (TiOPc) films as the donor layer. This type of films obtained through the weak epitaxy growth (WEG) method presents good continuity and integrity with the low density of grain boundaries. More importantly the films own a strong absorption in the NIR (750–950nm) and a broad absorption spectrum from 550 to 950nm. Meanwhile the high external quantum efficiency (EQE) is obtained in the NIR with the peak value over 38% and the EQE is over 18% in the entire response range, which could benefit from the long exciton diffusion length and the high carrier mobility of the highly ordered films. Thereby the fabricated planar solar cells achieve a high short-circuit current density (Jsc) of 9.26mAcm−2 and a power conversion efficiency (PCE) of 2.67%.