不同氧鈦比之氧化鈦分析及其於太陽能電池之應用

Abstract

溶液-凝膠法提供一種簡單的方式去改變材料的特性,例如:溫度、pH值…等，在這個研究中我們藉由調控氧化鈦溶液的反應時間進而合成出具有不同氧鈦比之氧化鈦，其材料特性會將隨之而發生改變，氧鈦比不同時，材料的能帶會有所改變，當氧鈦比增加，則材料的導帶及價帶能階越靠近二氧化鈦，其中導帶能階從3.92eV變化至4.32eV(二氧化鈦為4.37eV)，價帶能階從7.73eV變化至7.60eV(二氧化鈦價帶能階為7.58eV)，藉由將之導入所作之有機太陽能電池中，不同氧鈦比之材料會對元件表現產生影響。而我們發現具有低氧鈦比的氧化鈦在元件上能有較好的表現，這是由於其導帶能階位置與電子受體的最低未占分子軌道(LUMO)形成較為適當的條件，能夠有利於電子傳輸。 另一方面，有機太陽能電池雖具有許多優點(例如：低成本、易於大面積製作等)，但元件在大氣下容易使效率衰退，則為一重大缺點。然而，藉由導入氧化鈦作為水氧阻擋層，可以很明顯的看到元件大氣穩定性大幅上升，即使在大氣下長時間使用仍可保有不錯的效率。

Sol-gel method provide an easy way to modify the characteristics of material. In this study, we synthesis titanium oxide with different O/Ti ratio by sol-gel method but not by reactive sputtering. The characteristics of titanium oxide with different O/Ti atomic ratio is quite different, The band gap change with O/Ti ratio, when increase the O/Ti ratio, the conduction and valence band level more approach to the band position of titanium dioxide. The conduction band level change from 3.92 to 4.32 eV (the conduction band level of titanium dioxide is 4.37 eV), and the valence band level change from 7.73 to 7.60 eV (the valence band level of titanium dioxide is 7.58 eV). By introducing the TiOx into the device, the titanium oxide with the lowest O/Ti ratio is the best for electron transport layer of OPV, we consider that the conduction band level of TiOx approach to the LUMO of electron acceptor, result in a good condition for electron tansport. On the other hand, the air stability is a serious problems for the development of OPVs. The performance of device without protective layer degraded in the air dramatically. However, by introducing TiOx as a shielding layer, the device will remain high performance even storage in air for a long time.