Preparation Of TiO₂-NRs And NiO_x-NCs And Application In Perovskite Solar Cells

In recent years,Perovskite Solar Cells?PSCs?have attracted many researchers attention due to the unique properties of organic-inorganic hybrid perovskite materials,such as ultra-high electron mobility,long carrier diffusion length and high optical coefficient.And the power conversion efficiency?PCE?of organic-inorganic hybrid PSCs has increased from 3.8%in 2009 to the current record more than24.2%.However,in spite of these excellent optoelectronic properties,there are still some short slabs in organic-inorganic hybrid PSCs.Firstly,most high-efficiency PSCs utilize rigid FTO and ITO substrates,which are not approachable to practical applications and commercial production.Secondly,the device preparation process is complicated,for example,high-temperature sintering is required in the preparation process,a large amount of energy is consumed,and a certain degree of pollution has an adverse impact on the environment.In addition,charge loss and carrier recombination at the interface of the perovskite solar cells also seriously affect the PCE of the device.Therefore,it is important to improve devices performance and practical application by simplifying the fabrication process of the PSCs,eliminating the high-temperature sintering process,and modifying the cell interface.This thesis focuses on the preparation of flexible perovskite solar cells and the application of interface modification engineering in PSCs.It is mainly divided into the following three parts for exploration:?1?Flexible PSCs have attracted a great deal of attention in the field of thin film solar cells,due to the performance of light weight,flexible features and roll to roll fabricated process.Meanwhile,low temperature and solution processable nanoparticles provide an assess to prepare a simple and low-cost electron transporting lays?ETLs?.In this work,we assemble TiO₂-NCs doped TiO₂-NRs low temperature ETLs in flexible ITO substrates through using NOBF₄ to stripe OA and OAm long chain functional group.With the TiO₂-NRs properties of highly ordered structure and large specific surface area which can be attributed to form compact,smooth,transparent,and high electronic extract ability ETLs.To better summarize the optimum doping ratio of TiO₂-NRs into TiO₂-NCs ETLs,different volume ratios of TiO₂-NCs doped TiO₂-NRs ETLs were prepared,and the result indicated that the VRTiO₂-NRs/TiO₂-NCs=20%became a champion,which obtained highest power conversion efficiency?PCE?of 16.76%and average PCE of 16.08%with slightly hysteresis.This work will contribute to upgrading the flexible PSCs with a simple fabrication process and high device performance.?2?The organic-inorganic halide perovskite solar cells?PSCs?with charming photovoltaic properties still have some short slabs for further enhancement in device performance.The charge loss and carrier recombination at interfaces in the PSCs are crucial factors to inhibit the power conversion efficiency?PCE?.Here,we report a simple approach to overcome the drawbacks via modifying the interfaces between charge transport layers and perovskite layers in the PSCs with NiO_x nanocrystals?NiO_x-NCs?.The optimized device achieves a champion PCE as high as 19.47%.The interface engineering with NiO_x-NCs results in improved interface contact properties,enhanced charge transport dynamic and suppressed charge recombination in the corresponding devices,which further contribute to increased values of open-circuit voltage(V_oc)and short-circuit current density(J_sc).Therefore,this work supplies a novel guideline toward dual interfacial modification engineering to boost the performance of PSCs.?3?NiO is widely used in‘p-i-n”perovskite solar cells?PSCs?because of its low cost,good stability and high hole mobility.Since most of NiO requires a high temperature annealing process to achieve high hole mobility,and organic-inorganic hybrid perovskites do not have high temperature stability,it is rare to apply p-type NiO to perovskite solar devices.In this work,we improve the hole extraction rate by synthesizing low-temperature NiO_x-NCs and doping it into Spiro-OMeTAD as a composite hole transport layer which is used in“n-i-p”perovskite solar devices.Mainly increasing the V_oc and fill factor?FF?of the device And the PCE reached19.16%.This exploration provides new ideas for inorganic hole transport layers and dual hole transport layers.