Study On The Novel Polymer Solar Cells With Alcohol Soluble Interface Layer

Polymer solar cells (PSCs) have been extensively studied in recent years due to the great potential of low-cost energy conversion from solar light to electricity, light-weight and can be made flexible device. The performance of PSCs is rapidly approaching10%power conversion efficiency (PCE) and10years of operational stability by fine tailoring the molecular structure of donor and acceptor materials, optimizing the morphology of the photoactive layer, and engineering the photoactive layer/electrode interfaces. But the power conversion efficiency (PCE) and stability of the PSCs are still low in comparison with their inorganic counterpart. The acidic nature of PEDOT:PSS causes some corrosion problem on ITO, and the low-work-function metals are sensitive to oxygen and water which will degrade the stability of the PSCs. In this thesis, based on our laboratory conditions, in order to solve the existed problems of PSCs and grasp the research direction of PSCs, We choosed that the right alcohol-soluble chelate as an electrode buffer layer of materials in both conventional PSCs, which increased the power conversion efficiency and stability of the PSCs.We demonstrate high performance PSCs using solution-processed rhenium oxide (named as s-ReOx) as the anode buffer layer, selecting three representative polymer donors of P3HT, low bandgap copolymers PBDTTT-C and PBDTTT-C-T, and three representative fullerene derivative acceptors of PC60BM, PC70BM, and IC60BA. Compared with the PEDOT.PSS modified devices, the performance of the PSCs with s-ReOx anode buffer layer is greatly improved for all the tested devices. For P3HT:IC60BA-based PSC with s-ReOx anode buffer, the PCE reaches7.26%under the illumination of AM1.5G100mW/cm2. To the best of my knowledge, it is the highest value reported so far for the P3HT:IC6oBA-based PSCs. When using low bandgap polymer PBDTTT-C-T as electron donor, the PCE was improved to8.30%, with a enhancement of14%compared to the PEDOT:PSS-modified device.We report a solution-processed WO3(s-WO3) anode buffer layer that was prepared by spin-coating tungsten(VI) isopropoxide solution on an ITO electrode and then thermal annealing at150℃for10min in air, for the application in PSCs. The s-WO3layer shows a high hole mobility of9.4×10-3cm2/V·s and high light transmittance. The PSCs with the s-WO3anode buffer layer show enhanced photovoltaic performance in comparison with the devices with PEDOT:PSS as the anode buffer layer. The power conversion efficiency of the PSCs based on P3HT:IC70BA with the s-WO3anode buffer layer reached6.36%under the illumination of AM1.5G,100mW/cm2. The results indicate that s-WO3is a promising solution-processable anode buffer layer material for high efficiency PSCs and for the fabrication of flexible PSCs.Highly efficient PSCs are constructed by using alcohol soluble titanium chelate, Titanium(IV) oxide bis(2,4-pentanedionate)(TOPD), as electron collection layer, poly(3-hexylthiophene)(P3HT) as donor material and fullerene derivatives (PC60BM or PC70BM) as acceptor material. By introducing TOPD as electron collection layer, the PCE of the P3HT:PC60BM-based PSCs can be enhanced from2.72%up to3.65%under the illumination of AM1.5G,100mW·cm-2. When using PC70BM instead of PC60BM as donor, the PCE of the device can be further improved to3.96%. The improvement in device performance can be mainly attributed to the enhancement in electron mobility and decrease in the series resistance of the device upon insertion of TOPD buffer layer.