Cu/Cu2O composite films for novel perovskite solar cells and photodetectors

Abstract

In recent year the energy issues have been arguing endlessly From the stop nuclear power generation to the vote through on nuclear energy by referendum People are gradually realizing the importance of energy and never want to use “ love ” to generate electricity According to the announcement of the Taiwan Power Company the power generation structure of Taiwan in 107 year is mainly based on thermal power generation with fuel gas and coal burning of more than 80% Nuclear energy is 11 4% and other renewable pumping and steam energy sources are still less than 9% This shows that the form of overall power generation still has a negative impact on the environment As people's awareness of environmental protection rises thermal power generation will cause air pollution problems and the setting storage sites of nuclear wastes have become a topic of debate between public opinion and policy Countries around the world are actively developing and using clean renewable energy We hope to reduce and solve the pollution problems caused by traditional power generation in the most positive way and replace thermal and nuclear power with green energy Green energy power generation is commonly found in solar wind hydro and biomass energy generation While perovskite-based solar cells has grown very rapidly in just a few years which power conversion efficiency (PCE) has increased from the initial 3 8% to more than 24 2% it is considered to have great potential and can compete with crystal Si-based solar cells However due to the inherent defects of the perovskite it is susceptible to the external environment and the chemical reaction of the metal electrode makes the poor stability How to improve stability? The first way is to optimize the composition of the perovskite Although this method is very useful it is also very laborious On the other hand incorporating proper carrier transport layers and electrodes into perovskite-based solar cells is also considered as effective ways to maintain device stability as well as the efficiency of perovskite-based solar cells Therefore this study researches the effect of inorganic hole transport material Cu/Cu2O on perovskite solar cells to expect stability improved as well as the PCE increased The first part uses the ion beam sputtering system to deposit the Cu/Cu2O composite films by adjusting the ratio of argon and oxygen To keep the organic hole transport material Spiro-OMeTAD on the perovskite the organic material acts as a buffer layer so that the deposition of Cu/Cu2O does not damage the light absorbing layer perovskite The mobilities of Cu/Cu2O are at least three orders of magnitude higher than the organic hole transport layers of Spiro-OMeTAD In addition to helping the hole transport it also isolates the organic material from direct contact with the external atmosphere and the metal electrode effectively improving device efficiency and long-term stability The second part controlled the composition and thickness the transmission and conductivity of the Cu/Cu2O composite electrode have been optimized for efficient perovskite solar cells PCEs of 14 10% and 9 37% have been achieved for the bifacial-illuminated perovskite-based solar cell when the one sun AM1 5G illumination is incident from the fluorine-doped tin oxide (FTO) side and Cu/Cu2O side respectively This result opens up the possibility for a bifacial-illuminated devices in combination with a power-generating window in the building-integrated photovoltaics The third part of the photodetector is to use a Cu/Cu2O as the carrier transfer electrode to directly replace the organic hole transport material and the metal electrode This work reveals that the perovskite/(Cu/Cu2O) heterojunction photodetector a promising candidate for applications in bifacial-illuminated and flexible/wearable optoelectronic technologies

Date of Award	2019
Original language	English
Supervisor	Jung-Chun Huang (Supervisor)