The Effect Of Additive On The Morphology And The Performance Of Thiophene Polymer Photovoltaic Devices

Bulk heterojunction(BHJ) polymer solar cells (PSCs) is advantageous over inorganic photovoltaic devices due to their easy fabrication, low cost, light weight and flexibility in large-area applications. This article mainly studied the synthesis of polymer solar cell materials, the morphology and absorption spectrum of the blend films based PSCs.First of all, a new alternating copolymer (PBDTC10DBT) of benzo[1,2-b:3,4-b’]dithiophene (BDT) as donor and4,7-dithiophene-2-y1-2,1,3-benzothiadiazole (DBT) as acceptor, had been designed and synthesized in this work. We found that the polymer has a good electrochemical performance through characterization, such as a narrow bandgap of1.69eV,a deep HOMO level of-5.20eV.Secondly, this article studied that the different components of PC61BM impacted on the performance of the devices. The best performance of the device was obtained when PBDTC10DBT: PC61BM=1:2. In this case, the Voc of the device was0.658V, the Jsc of the device was4.61mA/cm2, the PCE of the device was1.57%.Finally, this article chose3solvents (1,8-octanedithiol,1,8-diiodooctane,1,8-dibromooctane) as additives, studied that the influence of additives on the morphology,the absorption spectra and photovoltaic performance of the polymer solar cells (PSCs) based on PBDTC10DBT:PC61BM systematically. Morphology of blend films and interpenetrating network between the donor and the acceptor phases were examined by using atomic force microscopy (AFM) and scanning electron microscope (SEM).We found that the PBDTC10DBT:PC61BM blend films with the trace amounts of additives were able to enhanced absorption and control the phase separation. The best results were obtained with3%1,8-diiodooctane as the processing additive, power conversion efficiency (PCE) of the PSCs was improved from1.57%to2.23%.Device production process was explored and provided a reference for controlling the morphology and microscopic phase separation of efficient photovoltaic devices through the study of this subject.