入射單色光-電子轉(zhuǎn)化效率(Incident Monochromatic Photon-Electron Conversion Efficiency,,IPCE)定義為流經(jīng)閉合電路中的電子數(shù)與入射單色光的光電子數(shù)的比值,,用來評價不同波長下的光電轉(zhuǎn)化效率,是評價光電極光電化學(xué)性能的重要指標(biāo)之一,。
由于半導(dǎo)體材料對不同波長的入射光具有不同的響應(yīng),,因此,測量光電極的IPCE對評估光電極對單色光光子的利用率會更加精確,,進(jìn)而在改進(jìn)光電極提升其光電化學(xué)性能上更具針對性[1],。
IPCE計算公式如下[2]:
jph:光電流密度(mA·cm-2),通過計時電流法(恒電位)測得
h:普朗克常量(6.62×10-34 J·s)
c:光速(3.0×108 m·s-1)
e:單個電子所攜帶的電量(1.6×10-19 C)
Pmono:單色光的光功率密度(mW·cm-2)
λ:單色光波長
簡化后可表示為公示(2)[1]:
jp:光電流密度(mA·cm-2)
jd:暗電流密度(mA·cm-2)
λ:入射單色光波長(nm)
pin:光電極受到的光功率密度(mW·cm-2)
光電極的光電流密度越大,,IPCE值越高,,可以通過改善光電極材料的電荷分離和收集效率,進(jìn)一步提升光電極的光電流密度,,從而提高IPCE數(shù)值,。
泊菲萊科技PL-PES光譜光電系統(tǒng)可實現(xiàn)以入射光的波長為函數(shù),在紫外,、可見,、近紅外波長范圍,自動表征測量半導(dǎo)體材料的光電流,、光伏等光電性能參數(shù),,可與開爾文探針、電導(dǎo)探針等測試設(shè)備聯(lián)用,,可以控制輸出光波長,、光照射時間、與電化學(xué)工作站同步工作,。PL-PES光譜光電系統(tǒng)主要應(yīng)用于不同外加電壓條件,、不同光照波長、不同光強(qiáng)和不同電壓及光照強(qiáng)度掃描下的光電流測試和特定光照波長下的開路電位測試等,。
Fig.1 a)PL-PES光譜光電系統(tǒng); b) IPCE曲線及光電流/電壓行為譜
Fig. 2. a) IPCE at 0 V vs. Ag/AgCl[3]; b) IPCE at 1.2 V vs. Ag/AgCl[4]; c)IPCE [5]; d) IPCE at 1.2 VRHE; e) band gaps from photocurrent measurements[6],;f) IPCEs at 0.6 and 1.2 VRHE, respectively[7]
參考文獻(xiàn)
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