Investigation on the Performance of Perovskite Solar Cells Based on All-oxide Charge Transport Layers

A perovskite solar cell with NiO and ZnO as charge transport layers was successfully fabricated. Intramolecular exchange technology was used to improve the morphology of CH3NH3PbI3 thin films. Doping was used to improve the conductivity of the NiO layer. X-ray diffractometer and scanning electron microscopy were used to analyze CH3NH3PbI3 thin films. A solar simulator with a digital source meter and quantum efficiency measurement system were used to test devices performance. The perovskite solar cells with FTO/p-NiO/CH3NH3PbI3/n-ZnO/Ag structure, have optimal PCE of 11.02% and long-term stability at 25 °C and 30 ± 2% humidity. This provides the possibility for the application of perovskite solar cells in the atmospheric environment. Introduction Various countries in the world have stepped up their efforts to develop new energy sources, duing to issues such as the energy crisis and environmental pollution. Recently, a new type of solar cell using an organic-inorganic hybrid halide perovskite as a light absorber has attracted the attention of many scientific researchers, which has the advantages of excellent performance, simple structure, and low preparation cost. The photoelectric conversion Efficiency has increased rapidly from 3.8% [1] to over 25.2% [2] in the past 10 years. The hole-transport materials currently used in such perovskite solar cells are usually organic polymers, such as Spiro-OMeTAD, PTAA [3], P3HT [4], PCBM [5], DEH [6], etc. Among them, spiro ometad device has the best performance, but the price is more expensive, 10 times of gold, which greatly improves the device cost, and the long-term stability of organic materials also needs to be further tested. Therefore, the development of high-efficiency and low-cost inorganic materials has become one of the important research directions of this kind of new solar cells. NiO is a p-type transparent oxide semiconductor with a wide band gap (Eg of 3.6 ~ 4.0 eV) and excellent performance. It has been successfully used as a hole-collecting and electron-blocking layer in dye-sensitized solar cells and organic solar cells. Compared with organic hole materials, NiO-based devices show better stability and comparable conversion efficiency [7]. Compared with TiO2, ZnO has a close band structure and higher electron mobility, which is 100 times that of TiO2 [8]. This enables photo-generated electrons to be more effectively injected into their conduction bands, and to transmit quickly to reduce electron losses and increase photocurrent. In addition, ZnO materials have the advantages of simple preparation, diverse morphology, and high crystal quality. These properties make ZnO the most ideal substitute for TiO2. In this work, NiO was used to replace the expensive and poorly stable Spiro-OMeTAD as the hole transport layer, and ZnO was used to replace TiO2 with low electron mobility as the electron transport layer. A perovskite solar cell with p-NiO/CH3NH3PbI3/n-ZnO simple sandwich structures were constructed and studied for their performance.