Simultaneous improvement in efficiency and transmittance of low bandgap semitransparent polymer solar cells with one-dimensional photonic crystals.

Abstract: One-dimensional photonic crystals (1DPCs) with the structure of (WO3/LiF) N are employed to simultaneously improve the efficiency and transmittance of low bandgap semitransparent polymer solar cells(PSCs). Within the photonic bandgap(PBG) of 580–780nm, 1DPCs with 8 pairs of WO3/LiF act as distributed reflectors (DBR), which reflects light wavelength of 580–780nm back into the PSCs for reabsorption by active layers. Power conversion efficiency (PCE) of 2.46% is obtained for the semitransparent PSCs and there is an improvement of 28.1% in the PCE when compared with that of the device without 1DPCs. Within the photonic passband of 380–580nm, the 1DPCs act as antireflection coatings. An average transmittance of 40% is remained within the wavelength range and the value is improved by 33% when compared with that of the device without the 1DPCs. Finally, it is demonstrated that the efficiency and transmittance of the device are dependent on the number of the repeated period (N). [Copyright &y& Elsevier]