The production and characterization of PCDTBT-based organic solar cells

In this study, Silver/n-type Silicon/poly[N-9′-heptadecanyl-2,7–carbazole–alt-5,5-(4′,7′-di–2–thienyl-2′,1′,3′-benzothiadiazole:[6,6]-phenyl-C61-butyric acid methyl ester/Gold (Ag/n-Si/PCDTBT:PC61BM/Au) organic metal-polymer semiconductor Schottky barrier diodes were produced by using PCDTBT:PC61BM mixtures with percentage ratios of %66:34%, 50%:50%, and 20%:80% as a polymer interface. The ideality factor (n), saturation current (I0) and potential barrier height (ϕ0) values of the produced diodes were investigated by employing Current-Voltage measurements in the temperature range of 240 – 350 °K. The ideality factors for %66:%34, %50:%50, and %20:%80 mixture ratios were found to vary between 2,29-3,82; 1,38-1,53 and 1,80-2,26, respectively.The optical properties of the mixtures used in the diodes were investigated by transmission measurements in the wavelength range of 400-1100 nm after coating of PCDTBT:PC61BM thin films with mixture ratios of 66%:34%, 50%:50%, and 20%:80% on a glass substrate. The forbidden band gap for the investigated films were found to be indirect in nature and the band gap energy values were found to be 1,03; 0,84 ve 0,84 eV for films with the ratios %66:%34, %50:%50, and %20:%80, respectively. In the final stage of the study, Indium Tin Oxide/PCDTBT:PC61BM/Silver (ITO/PCDTBT:PC61BM/Ag) organic solar cells were produced by using 66%:33%, 50%:50%, and 20%:80% PCDTBT: PC61BM mixture ratios. The optoelectronic properties of the produced solar cells were investigated by employing Current Density-Voltage measurements at 300°K room temperature under AM 1.5 solar radiation. As a result of the analysis, maximum power density (Pmax), fill factor (FF) and power conversion efficiency (η) values were calculated for all of the produced cells. As a result of calculations, solar power conversion efficiencies of 0.39%, 0.57% and 0.85% were calculated for the cells having 66%:34%, 50%:50%, and 20%:80% PCDTBT:PC61BM mixture ratios. It was also revealed that the increase of percentage ratio of PC61BM in solar cells significantly increased cell power conversion efficiency. Keywords: PCDTBT, PC61BM, solar cell, electrical characterization, optical characterization