Efficient organic optoelectronics with multilayer structures

Abstract

In this study we developed efficient polymer solar cells (PSCs) and polymer light emitting diodes (PLEDs) incorporating multilayer structures prepared through solution processing. To prevent dissolution of the bottom layer by the subsequent layer, we used a polydimethylsiloxane stamp to transfer the film onto the target surface. The active layer of the PSCs consisted of a poly(3-hexylthiophene) (P3HT)-rich layer and a [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM)-rich layer; the active layer of the PLEDs consisted of a blue-polyfluorene as the light emitting layer (LEL) and poly(9,9-di-n-octylfluorene-alt-(1,4-phenylene-((4-sec-butylphenyl)imino-1,4-phenylene))) (TFB) as the electron blocking layer (EBL). We found that the efficiency of devices was readily manipulated by changing the constitution of each stacking layer. After optimizing the fabrication conditions for each functional layer, we obtained PSCs reaching a power conversion efficiency of 3.52%. The efficiency of PLEDs incorporating an EBL was 27% greater (reaching 4.7 cdA⁻¹) than that prepared without an EBL layer.