| Energy sources crisis has become the most problem of human being, since the traditional energy sources (i.e. coal, oil and natural gas) have almost been used up. Solar cells, which based on the semiconductor, can change the optical energy into electrical energy directly, have been received lots of attention. Organic polymer solar cells (PSCs) with its special superiority have great competitive power and commercial potential. Such as plenty of choices for the active layer, which can be made from molecular design and chemical synthetizing; light-weight, can be compatible with flexible substrate; preparation can be easily control and large-scale by spin-coating, ink-jet printing and screen-printing. However, there is still a large distance of power conversion efficiency (PCE) between inorganic semiconductor solar cells and PSCs. Up to now, all of the researching work are hammered at improving PCE of PSCs.This thesis is mainly discussing how to optimize the PSCs performance in order to solve the problems of PSCs existed. We divided the optimizing process into four parts, the main content and conclusions are as follows:1:We investigate the effect of the post-additional thermal annealing (PATA) treatment on the performance of PSCs. The results indicate that the crystallization and the surface roughness of RR-P3HT are both improved after PATA compared with those after traditional post-production thermal annealing (TA) treatment. The better interpenetrating network formed between RR-P3HT and PCBM is convenient for charge transfer and extraction, therefore the PCE of PATA device is improved by about11%. Our results suggest that PATA treatment is an easy and feasible way to conduct, and will be of great importance for large-scale fabrication of PSCs.2:We investigated the effects of annealing rate and morphology of sol-gel derived zinc oxide (ZnO) thin films on the performance of inverted polymer solar cells (IPSCs). The undulating morphologies of ZnO films fabricated at annealing rates of10℃/min and3℃/min each possess a rougher surface than that of the ZnO film fabricated at a fast annealing rate of50℃/min. The results indicate that the ZnO film formed at3℃/min possesses a good-quality contact area with the active layer. Combined with a moderate light-scattering, the resulting device shows a16%improvement in power conversion efficiency compared with that of the rapidly annealed ZnO film device.3:We demonstrated sol-gel textured Al-doped ZnO (AZO) cathode buffer layer induced further light absorption at near-UV/blue light region (300-500nm) of the active layer in IPSCs. Due to the enhanced absorption, the short current density of thetextured-AZO device is increased from9.52to11.30mA/cm2compared with the reference cell based on the flat-AZO. Power conversion efficiency is increased substantially from2.44%to2.87%since without loss in the fill factor and open circuit voltage.4:We fabricated a solution processed Polyvinylpyrrolidone (PVP) thin film used as the surface modifier for AZO in IPSCs. The PVP device based on P3HT:PCBM demonstrated an improved PCE by45%than the device without the PVP interfacial layer. Significantly enhanced FF was attributed to the excellent interface property, effective electron selectivity and collection ability, which provided by the PVP surface modifier. By further optimizing the hole transport layer, a high efficiency of4.6%was achieved. Our result provides an easy method for optimizing the interface of IPSCs. It is fully compatible with large area roll-to-roll production techniques, owning to the fabrication does not require chemical synthesis and can be easily conducted at room temperature in air. |
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