Study On Normal, Inverted And Tandem Polymer Solar Cells Based On P3HT

Polymer solar cells (PSCs) have become a popular research field, due to their advantages of low cost、ease of fabrication、light weight and flexibility. This paper mainly reports P3HT-based PSCs with different structures, including normal、inverted and tandem structure devices. The results are as follow:1. The normal PSCs with a structure of FTO/MoO3/P3HT:PCBM/Al have been fabricated using poly(3-hexylthiophene)(P3HT) as the electron donor and [6,6]-phenyl C61butyric acid methyl ester (PCBM) as the electron acceptor. The performances of the PSCs are enhanced by optimizing the thermal annealing times (t=0、2、5、10and15min) which improve the P3HT crystallinity and avoid the serious phase separation of the P3HT:PCBM active layers. The PSCs exhibit a open-circuit voltage (Voc) of0.56V, a short circuit current density (Jsc), a fill factor (FF) of61.0%and a power conversion efficiency (PCE) of3.60%under illumination of AM1.5G,100mWcm-2.2. The normal PSCs with a structure of FTO/Mo03/P3HT:IC7oBA/Ca/Al have been fabricated by using P3HT as the electron donor and IC70BA as the electron acceptor. The performances of the PSCs are enhanced by adjusting the spin-coating times (ts=20、25、30、35、40and45s) of the P3HT IC70BA blend solution, which control the solvent annealing time (ta=60、50、30、16、6�'�1min) of the P3HT:IC7oBA active layers。The optimized PSCs exhibit a Voc of0.85V, a Jsc of10.61mA/cm2, a FF of74.1%and a PCE of6.68%under illumination of AM1.5G,100mWcm-2.3. Flake-like Al-doped ZnO (AZO) nanostructures were obtained via a low-temperature (100℃) hydrothermal process. By doping Al and varying its concentrations, the electrical conductivity and surface morphology of the AZO nanostructures can be readily controlled. The effect of the electrical conductivities and surface morphologies of the AZO nanostructures on the performances of the inverted PSCs with a structure of FTO/ZnO/Al-ZnO/P3HT:PCBM/MoO3/Al are studied. It presents that the optimized PCE of the AZO-based PSC is improved by approximately 58.7%compared with that of un-doped ZnO-based PSCs. It is attributed to that the flake-like AZO nanostructures of high electrical conductivity and tunable morphology not only provide a high-conduction pathway to facilitate electron transport but also lead to a large interfacial area for exciton dissociation and charge collection by electrodes.4. The inverted PSCs with a structure of FTO/TiO2/CsOx/P3HT:ICBA/MoO3/Al have been fabricated using P3HT as the electron donor and ICBA as the electron acceptor. The inverted PSC exhibit a PCE of5.65%, which is higher by11.4%and11.5%than that of the inverted PSC with single TiO2and CsOx, respectively. This improved performance can be attributed to the compound buffer layer which can enhance electron extraction capacities and suppress leakage current. Moreover, the highest PCE of3.76%of the P3HT:PCBM inverted PSC with TiO2/CsOx buffer bilayer is achieved by replacing P3HT:ICBA active layer with P3HT:PCBM active layer.5. We report an efficient tandem PSC, consisting of two active layers of P3HT:PC61BMandpoly[{2,5-bis(2-hexyldecyl)-2,3,5,6-tetrahydro-3,6-dioxopyrrolo [3,4-c]pyrrole-1,4-diyl}-alt-{[2,2’-(1,4-phenylene)bisthiophene]-5,5’-diyl}](PDPPTP T):PC61BM. The two active layers are connected by a Ca (1nm)/Ag (1nm)/MoO3(10nm) intermediate layer, which is superior to the Ca (1nm)/Al (1nm)/MoO3(10nm) intermediate layer for better performance. The tandem PSC with complementary spectral absorption of300-850nm shows a PCE of4.50%under AM1.5G,100mW cm-2illumination and an efficiency improvement of～25.0%over the single-stack sub-cells.