本研究以p型無機半導薄膜氧化鎳(NiOx)作為電極接面層應用於鈣鈦礦太陽能電池中取代一般常用之有機電洞傳輸層材料PEDOT:PSS以提升太陽能電池光電轉換電效率。氧化鎳之光穿透率(transmittance)、表面形態和功函數(work function)與熱氧化溫度相關。當氧化鎳之熱氧化溫度上升時，光穿透率與功函數也會隨之上升。以450 度C熱氧化之氧化鎳其功函數為5.4 eV接近CH3NH3PbI3的HOMO能階，由於能階之匹配可減少電洞在接面傳導時的能量損耗進而提升電洞傳輸效率。以氧化鎳作為電極接面層(電洞傳輸層)之鈣鈦礦太陽能電池元件最好的表現達到短路電流JSC=13.16 mA/cm2，開路電壓VOC=0.901 V與光電轉換電效率為7.75%。
由於氧化鎳的導電率較差，因此不足以單獨作為透明導電電極(TCO)，因此在本研究中進一步將常使用於LED製程中之熱氧化鎳金(Ni/Au)電極來取代NiOx/ITO與PEDOT:PSS電極結構。於基板上鍍製鎳金雙層結構，再進行高溫退火，鎳金雙層結構在退火時，鎳原子經由金之晶界擴散出表面後氧化形成氧化鎳(NiOx)，而金(Au)則形成網狀結構(network structure)，此氧化鎳適合應用於鈣鈦礦太陽能電池中作為電洞傳輸之接面層並可作為電子阻擋層。熱氧化鎳金電極(Au:NiOx)作為透明導電電極，可簡化製程，降低成本，並可提高鈣鈦礦太陽能電池元件之操作穩定性。以Au:NiOx透明導電電極應用於鈣鈦礦太陽能電池元件中，最好的元件特性其開路電壓為VOC=1.02 V, 短路電流JSC=13.04 mA/cm2，填充因子FF=77% 與光電轉換電效率為10.24%。
此外，我們將低溫濺鍍之氧化鋅(ZnO)薄膜應用於倒置型鈣鈦礦太陽能電池結構中作為電子傳輸層，氧化鋅具有與鈣鈦礦吸收層之LUMO能階(3.9 eV)相近之導帶能階(4.2 eV)可有效提升電子傳輸效率。但氧化鋅之濺鍍製程中電漿過程會使鈣鈦礦薄膜因電漿轟擊而損傷，進而導致元件失效。因此在本研究中，使用C60來做為保護層且C60之導帶能階(4.1 eV)與鈣鈦礦、氧化鋅有良好之能階匹配，可降低電子傳輸能量損失。以C60/氧化鋅作為電子傳輸層之鈣鈦礦太陽能電池元件由無光電轉換電效率提升至短路電流JSC=19.41 mA/cm2，開路電壓VOC=0.91 V，與光電轉換電效率為10.93%。

In this study, we successfully applied a thin, p-type, semiconducting, inorganic NiOx layer as substitute for PEDOT:PSS, and the perovskite-based solar cells consisting of NiOx as electrode interlayer improve device performance. The transmittance, surface morphology, and work function of Ni-oxidized NiOx are strongly related to the Ni oxidation temperature. The transmittance and work function increased in accord with the increased oxidation temperature of the Ni-oxidized NiOx layer. The larger transmittance and work function of Ni-oxidized NiOx can result in less light absorption and hole transport energy loss, respectively. The CH3NH3PbI3 perovskite-based solar cells with a NiOx hole transport layer yield better short circuit current density of 13.16 mA/cm2, open circuit voltage of 0.901 V, and power conversion efficiency of 7.75% than that of CH3NH3PbI3 perovskite-based solar cells with a PEDOT:PSS interlayer.
However, the electric conductivity of NiOx layer is still insufficient to be solely used as the transparent conductive oxide (TCO) electrode. We then proposed oxidized Ni/Au transparent electrode as replacement for NiOx/ITO layers of perovskite-based solar cells. This work first and successfully demonstrates the application of the well-developed nickel (Ni)/gold (Au) transparent electrode in GaN light-emitting diodes industry for fabricating efficient perovskite-based solar cells. To prepare the electrode and the electrode interlayer in one single process simplifies fabricating procedures, and poses to the new design of the functionalized electrode in perovskite-based hybrid devices. The combination of NiOx with the interconnected network Au forms a functionalized Au:NiOx electrode, capable of transporting holes and blocking electrons from CH3NH3PbI3 perovskite to reach the electrode. Changing Ni/Au compositions and the thermal treatment conditions modulates the optical transparency, electrical conductivity, the work function of Au:NiOx electrode, as well as the photovoltaic parameters of hybrid cells. The cell with the configuration of glass/Au:NiOx/CH3NH3PbI3 perovskite/C60/BCP/Al is free of the ITO electrode and PEDOT:PSS interlayer to achieve an open circuit voltage of 1.02 V, a short circuit current density of 13.04 mA/cm2, and a fill factor of 77%, corresponding to a decent power conversion efficiency of 10.24% under standard 1 sun AM 1.5G simulated solar irradiation.
In addition, we have demonstrated the performance of inverted CH3NH3PbI3 perovskite-based solar cells with a room temperature (RT) sputtered ZnO electron transport layer by adding fullerene (C60) interlayer. ZnO has a matched conduction band level (4.2 eV) with the unoccupied molecular orbital (LUMO) level of perovskite (3.9 eV), which can enhance the transport efficiency of photo-generated electron to escape solar cells. However, the CH3NH3PbI3 perovskite layer will be damaged during direct RT sputtering deposition of ZnO. Therefore, the C60 interlayer having matched conduction band level with ZnO and CH3NH3PbI3 perovskite added between the CH3NH3PbI3 perovskite and RT sputtered ZnO layers for protection prevents sputtering damages on the CH3NH3PbI3 perovskite layer. The short circuit current density (19.41 mA/cm2), open circuit voltage (0.91 V) and power conversion efficiency (10.93%) of the solar cells with glass/ITO/PEDOT:PSS/perovskite/
C60/RT sputtered ZnO/Al structure is higher than the JSC (16.23 mA/cm2), VOC (0.90 V) and power conversion efficiency (10.6%) of the solar cell with glass/ITO/PEDOT:PSS/perovskite/C60/BCP/Al structure.

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