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來源：福建物(wu)質(zhi)結(jie)構(gou)研(yan)究(jiu)(jiu)所近(jin)(jin)年來，無鉛金屬鹵化物(wu)雙鈣鈦礦Cs2Na(Ag)InCl6材(cai)(cai)料因組份易(yi)調控、合(he)成簡便及毒性低(di)(di)等特性，而備受關注，在(zai)照明顯(xian)示、光(guang)(guang)(guang)電(dian)(dian)探測及光(guang)(guang)(guang)伏等領域(yu)表(biao)現出(chu)廣闊的(de)應用潛力。目前，該材(cai)(cai)料的(de)研(yan)究(jiu)(jiu)主要局(ju)(ju)限(xian)(xian)在(zai)可(ke)見(jian)(jian)光(guang)(guang)(guang)波(bo)段，近(jin)(jin)紅外（NIR）波(bo)段存在(zai)發光(guang)(guang)(guang)效(xiao)率低(di)(di)的(de)瓶(ping)頸，制(zhi)約(yue)進一步(bu)的(de)應用開發。針對此問題(ti)，中(zhong)(zhong)(zhong)(zhong)國(guo)科學(xue)院福建物(wu)質(zhi)結(jie)構(gou)研(yan)究(jiu)(jiu)所和(he)閩都創(chuang)新實驗(yan)室(shi)研(yan)究(jiu)(jiu)員陳學(xue)元課題(ti)組，通過(guo)在(zai)Cs2NaInCl6中(zhong)(zhong)(zhong)(zhong)引入稀土離子(zi)Yb3+和(he)Er3+作為近(jin)(jin)紅外發光(guang)(guang)(guang)中(zhong)(zhong)(zhong)(zhong)心，實現高(gao)效(xiao)近(jin)(jin)紅外發光(guang)(guang)(guang)（圖1）。Cs2NaInCl6:Yb3+的(de)最佳(jia)量(liang)子(zi)產率為39.4%，相比(bi)(bi)Cs2AgInCl6:Yb3+材(cai)(cai)料提(ti)升了(le)(le)142.2倍。科研(yan)團隊通過(guo)第一性原理計算(suan)和(he)Bader電(dian)(dian)荷(he)分(fen)析，對比(bi)(bi)研(yan)究(jiu)(jiu)了(le)(le)Cs2NaInCl6:Yb3+和(he)Cs2AgInCl6:Yb3+兩(liang)種材(cai)(cai)料的(de)局(ju)(ju)域(yu)電(dian)(dian)子(zi)結(jie)構(gou)（圖2）。Bader電(dian)(dian)荷(he)分(fen)析是一種通過(guo)將材(cai)(cai)料的(de)總電(dian)(dian)荷(he)分(fen)解(jie)到原子(zi)電(dian)(dian)荷(he)，得到原子(zi)周圍電(dian)(dian)子(zi)數(shu)，進而計算(suan)出(chu)原子(zi)化合(he)價的(de)方法。該方法應用于(yu)材(cai)(cai)料的(de)電(dian)(dian)荷(he)特性分(fen)析，判(pan)斷材(cai)(cai)料內(nei)電(dian)(dian)荷(he)傳輸過(guo)程。研(yan)究(jiu)(jiu)表(biao)明，Cs2NaInCl6:Yb3+中(zhong)(zhong)(zhong)(zhong)Na+離子(zi)的(de)強離子(zi)性使其(qi)幾乎完全電(dian)(dian)離，導致相鄰的(de)[YbCl6]八面(mian)體電(dian)(dian)荷(he)顯(xian)著(zhu)局(ju)(ju)域(yu)化，促進了(le)(le)Cl--Yb3+的(de)荷(he)移(yi)躍(yue)遷。而Cs2AgInCl6:Yb3+中(zhong)(zhong)(zhong)(zhong)的(de)Ag+由于(yu)強共價性形成Ag-Cl共價鍵，使相鄰的(de)[YbCl6]八面(mian)體中(zhong)(zhong)(zhong)(zhong)Cl-的(de)電(dian)(dian)子(zi)波(bo)函(han)數(shu)向(xiang)Ag+離域(yu)，導致Cl-與Yb3+波(bo)函(han)數(shu)交疊(die)減小，從而抑制(zhi)了(le)(le)Cl--Yb3+荷(he)移(yi)躍(yue)遷過(guo)程。該研(yan)究(jiu)(jiu)利用溫度(du)依賴的(de)穩態(tai)(tai)和(he)瞬態(tai)(tai)熒(ying)光(guang)(guang)(guang)光(guang)(guang)(guang)譜(pu)等手段，觀察到Cs2NaInCl6:Yb3+中(zhong)(zhong)(zhong)(zhong)Yb3+的(de)激發峰相對于(yu)基(ji)質(zhi)自限(xian)(xian)激子(zi)的(de)激發峰存在(zai)明顯(xian)偏移(yi)（圖3）。在(zai)低(di)(di)溫下，Cs2NaInCl6:Yb3+通過(guo)紫外激發，在(zai)近(jin)(jin)紫外-可(ke)見(jian)(jian)光(guang)(guang)(guang)區觀察到兩(liang)個發射峰，波(bo)數(shu)差約(yue)為9766 cm-1，對應于(yu)荷(he)移(yi)躍(yue)遷帶(dai)（CTB）→2F7/2和(he)2F5/2躍(yue)...