The Application Of Chalcogenide Semiconductor Materials In Photovoltaic Devices

Our work has gone through Materials preparation,Devices design,Device Fabrication,optimize experimental of different structures and different layers.And we finally succeeded in analysing and explaining the reason of some well worked and efficient divices.The materials’property and whether their band matching well between diffdrent layers are some of the factors that influenced the devices’performance.These ideas were come out through analyzing different experimental results and the test results of devices with different structures,such as devices with different kinds of active layers or devices with different kinds of buffer layers.Different materials result difference interface structures,that is to say the the optical-electrical properties and microscopic structure of the buffer layer will affect the photoelectric properties of the device directly.It means that the microstructure of the active layer affects the performance of the device,and Searching for a better buffer layer is of great help to improve the performance of the device.Compared with organic and polymer photovoltaic solar cells,Pb S and Cd Se materials benefit from the solution treatment.Solar cells by using narrow band materials such as PbS and CdSe nanoparticles can absorb most of the solar spectrum energy including some infrared ray.PbS and CdSe have very large dielectric constant.So they haVe large exciton Bohr radius what led to deep quantum confinement.But PbS limited by a very narrow energy gap（0.41eV）,CdSe also has narrow energy gap.But by increasing the Quantum confinement,band gap could increase to a new width.PbS and Cd Se nanoparticles that we need are synthesis using the following method in this article successfully.PbS inverted structure QDs cells were deposited using the layer by layer（LBL）method.simple thiol molecules can remove oleic acid effectively,and get a very strong electronic coupling.Mercaptopropionic acid often been chosen in the fabrication of PbS quantum dot solar cell.Studies have shown that PbS solar cells’optical and electrical performance benefit from the use of thiols.Heat treatment would remove volatile small molecules like methanol molecules,and made the random displacement lattice atoms return to their original position.The stability of the device gave a pleasing performance.Efficient PbS quantum dot（QD）solar cell with the traditional structure requires an inorganic buffer layer that is usually fabricated at high temperature,which is not compatible with the industrially preferentially roll-to-roll fabrication process.Searching a suitable buffer layer and constructing the devices in an efficient way are thus of particularly significant.Herein,we fabricate PbS quantum dot solar cells in an inverted structure using poly（thiophene）（3,4-ethylenedioxythiophene）/poly（styrenesulfonate）（PEDOT:PSS）as the anode buffer layer.The resulting devices present a high efficiency of 4.1%,among the best values of inverted PbS QDss solar cells.The experiment proved that through using different buffer layers can improve the performance of PbS device obviously.The energy band of the PEDOT buffer layer and NiO buffer layer matching well with PbS quantum dot film as well as their matching impedance.The optimizing of the interface and the impedance of the device at the same time has a positive effect in improve the performance of the device and in scientific research.using the method in this article,An optimal-device with the Voc=0.48V,Jsc=20.1mA/cm²,FF=43.2%,PCE=4.1%and PCE=4.1%was abricate out successfully.Electrochemical and optoelectrical characterization have shown that,compared with high-temperature annealed NiO and V₂O₅ layers,the low-temperature processed PEDOT:PSS layer has a more compatible film properties for efficient injection and collection of charges from PbS QDss active layer.Our experiment significantly enhanced the performance of the Pb S-QDs solar cell,and proved that the interface design of device and the method of introducing buffer layers with different materials are effective experimental methods and good strategy in improving the performance of the device.Our work provides a promising strategy for fabrication of QD solar cells in an economical and efficient way.Constructing a highly efficient bulk-heterojunction is of critical importance to the hybrid organic/inorganic solar cells.Here in this work,we provide a novel hybrid architecture adopting P3HT nanowire and CdSe nanotetrapod as bicontinuous charge channels for holes and electrons,respectively.Compared to the traditionally applied P3HT molecules,the well crystallized P3HT nanowires qualify an enhanced light absorption at the long wavelength as well as strengthened charge carrier transport in the hybrid active layer containing P3HT nanowires and CdSe nanotetrapods.Accordingly,based on efficient dissociation of photogenerated excitons,the interpercolation of these two nanobuilding blocks allows a photovoltaic conversion efficiency of 1.7%in the hybrid solar cell,up to 42%enhancement compared to the reference solar cell with traditional P3HT molecules as electron donor.Our work provides a novel hybrid structure for promising organic/inorganic bulk-heterojunction solar cells.Moreover,we demonstrated a planar solar cell of CH₃NH₃PbI₃ with CdSe as the electron transfer/extraction layer successfully.A new structure like ITO/PEDOT:PSS/CH₃NH₃PbI₃/CdSe/Ag is a scientific and efficient design,demonstrated by our improvement works.An efficiency about 14%was obtained by our experiments.CdSe nanocrystals were used as electronic extraction layer of the CH₃NH₃PbI₃ devices considering its’high electron mobility and can be treated in solution with low temperature.The results show that CdSe nanocrystals is an efficient electron transfer/extraction material,which can effectively reduce the cost of device compared with expensive PCBM material,which provides a new method for the design of the charge extraction functional layer for the Perovskite cells.