The study on organic solar cells based on bathocuproine as an exciton blocking layer

Abstract

Using a buffer layer between C₆₀ and cathode was an important and popular approach to improve the performance of organic photovoltaic cells. In this work, we chose CuPc (Copper(II) phthalocyanine) as an electron donor material, C₆₀ (fullerene) as an electron acceptor material and BCP (Bathocuproine) as an exciton blocking layer to fabricate an organic solar cells with a structure of ITO/CuPc/C₆₀/BCP/Ag, and studied the relationship between the photoelectric properties of organic solar cells and the film thickness of BCP. The results showed that the power conversion efficiency (PCE) was closely related to the thickness of exciton blocking layer. With the increasing of BCP film thickness, the power conversion efficiency of the device increased first and then decreased. When the thickness was 0 nm, the power conversion efficiency (PCE) was 0.357 %. When the film thickness was 25 nm, the PCE was 1.013 %. And when the thickness was 50 nm, the PCE was 0.43 %. However, when the thickness was 100 nm, the PCE was 0 %.We presumed that the exciton blocking layer reduce the quenching rate at the interface between organic layer and cathode so that exciton can be separated into electrons and holes more effectively. As a result, the PCE increased. At the same time, if the film of BCP layer thickness is too thick, PCE would sharply decrease due to high resistance during collecting charge carriers.