Perovskite Solar Cells And Quantum Dots Solar Cells Based On Cds As Electron Transport Layer

Cadmium sulfide（CdS）is a traditional inorganic metal sulfide n-type semiconductor material with a comparable band gap（2.4 eV）,and can act as the electron transport layer material.Compared with the current electron transport layer of metal oxides,the film-forming temperature of CdS is very low,which can be applied to flexible devices.Compared with high-purity and expensive organic n-type semiconductor materials,the cost of CdS is very cheap and the preparation process is very simple.This paper designed the perovskite solar cells and PbS quantum dots solar cells based on CdS as electron transport layer,and the results are as follows:1.We used a chemical bath method to prepare a compact and smooth CdS film covering the FTO substrate.By controlling the deposition time,the thickness of CdS film can be adjusted.A one-dimensional CdS nanorod arrays structure was synthesized by chemical water bath method and hydrothermal method.The nanorods were perpendicular to the FTO,and the diameter was about 60-100 nm.Control of the density of CdS nanorods can be achieved by regulating the hydrothermal time.CdS materials absorbed the light below 500nm,which was related to its band gap.2.We constructed 3D architecture perovskite solar cell by using CdS NR arrays as the electron transport layer.The perovskite film was prepared by physical and chemical vapor deposition method,which realized the preparation process of perovskite without solution and solved the problem of decomposition and low coverage of perovskite film caused by spin-coating method.At the same time,the perovskite layer was closely combined with the CdS nanorod arrays layer.The nanorod provided a one-dimensional transport path that facilitated the transmission of electrons.The 3D structure increased the area of heterojunction,which was beneficial to the separation of carrier.The density of the nanorod arrays had a great influence on the performance of perovskite solar cell.Finally,when the hydrothermal time was 12 hours,we got the best power conversion efficiency of 12.46%with V_oc of 1.01V,J_sc of 19.88mA cm^-2 and fill factor of 62.06%,which was equivalent to four times the efficiency of perovskite solar cell with a same thickness of CdS film.After four days of stability testing,the solar cell can still maintain the original efficiency of 73%.3.High quality PbS QDs were prepared by cation exchange method.A PbS quantum dot solar cell device was prepared by using CdS film.The sulfur powder with low price and low toxicity,instead of volatile,expensive and toxic hexamethyldisilathiane,was the initial source of sulfur.CdS was synthesized using sulfur powder by hot injection method.We synthesized PbS QDs of 2-4 nm by controlling the size and concentration of CdS QDs.Surface of the PbS QDs are modified by tetra-butyl iodide and ethylene glycol.By adjusting the thickness of the CdS layer and the number of PbS layers,the power conversion efficiency of 3.18%with V_oc of 0.36V,J_sc of 24.45mA cm^-2 and fill factor of 36.12%was finally realized.After 30 days of stability testing,the solar cell showed good stability.