Preparation Of Novel Semicondutor Nano-crystals And Their Application For Sola Cell

This work focuses on new type nano-materials based heterojunction solar cells. Firstly, semiconductor nano-materials are synthesised. Secondly, two types of pho-tovoltaic device are designed and fabricated. and then tests the performance of those trial PV power generation. Thirdly, the devices are tested for their performance on PV power generation. The main researches are drawn as following.1. Because of the quantum effects, many inorganic semiconductor nanomate-rials show unique optical or electrical properties, which are expected to be used in the photovoltaic field. In this work, well-dispersed and uniform-sized nanocrystals of CdSe, ZnO and FeS2 materials are successfully synthesized through a simple me-thod in the liquid phase. Their physical and chemical properties are characterized with UV, PL, XRD and TEM. The CdSe nanocrystals are prepared through the mean of hot-injection. The diameter of this nanocrystals is destributed from 3.7 to 4.3nm and the band gap is about 2.15 eV. The ZnO nanocrystals are synthesized through the mean of chemical liquid deposition. The diameter of this nanocrystals is about 5nm and the band gap is about 3.72eV. The novo FeS2 nanocrystals are synthe-sized by the mean of hot injection, to which the detailed synthesis method of II-VI quantum dots is referred. The diameter of this nanocrystals is distributed from 7.5 to 9.5 nm and the band gap is about 1.1-1.2eV.2. According to the band energy levels of each nanocrystals and their rela-tionships, two new types of nano-materials besed heterojunction solar cells are de-signed: solar cell A (ITO/PEDOT:PSS/CdSe/ZnO/Al) and solae cell B (ITO/ PEDOT:PSS/P3HT/FeS2/Al). The thickness of each layers are several tens of na-nometers, and total thickness of the device (excluding the substrate) is about several hundred nanometers, which is well lower than the silicon-based solar cells (ca.400 u m). 3. In this experiment, ITO glass substrates were prepared by spin-coating film electrode in the vacuum evaporation, the final package in the glove box into a com-plete photovoltaic devices. In order to achieve higher energy transforming efficiency, some detailed treatments are applyed to the preparation process as followed. The original insulated long-chain orgnic ligands of newly prepared CdSe and FeS2 nano-crystals are exchanged to highly conductive pyridine ligands, in order to reduce the distance among the nanoparticles and to gain the carrier conductivity. By the injec-tion of benzenedithiol, a di-coordination bands lignad, the CdSe nanocrystals are crosslinked to a close and well-organized arrangement, which can help reduce the composition in carrier transduction process.4. The trial device was tested under standard testing conditions, the measured solar cell A shows an open circuit voltage (Voc) of 0.46 V, a short circuit current density (Jsc) of 1.01 mA/cm2, a fill factor (FF) of 0.29 and a power conversion effi-ciency of 0.13%. Solar cell B shows an open circuit voltage (Voc) of 0.38 V, a short circuit current density (Jsc) of 1.69 mA/cm2, a fill factor (FF) of 0.35 and a power conversion efficiency of 0.23%.