結合電性量測與等效電路模型於低溫與低頻率之鈣鈦礦太陽能電池深缺陷分析

Abstract

鈣鈦礦太陽能電池（Perovskite Solar Cells, PSCs）因其高光吸收係數、可調整的能隙、低製成溫度等優點，在過去十年間受到廣泛關注。然而，其材料內部與面所形成的缺陷，仍嚴重限制元件的穩定性與性能表現。因此，發展一套能在不同溫度與頻率下有效探測與分析缺陷性質之方法，對於未來太陽能電池製成優化與結構設計具有相當關鍵的意義。本研究針對同一個反式 P-I-N 鈣鈦礦太陽能電池，結合多項電性量測技術與等效電路分析模型，系統性的探討鈣鈦礦太陽能電池於低溫與低頻環境下之缺陷特性 。 使 用 之 量 測 方 法 包 含 ： DLCP （ Drive-Level Capacitance Profiling ）、 CV（Capacitance-Voltage）、TAS（Thermal Admittance Spectroscopy）、DLTS（Deep LevelTransient Spectroscopy），並利用 IS（Impedance Spectroscopy）結果建立等效電路模型。所有實驗針對同一元件進行，並於實驗前後分別進行照光之 IV 測試，以確認離子分布不受長時間且重複的電性量測影響。其反向 IV 的光電轉換效率由原來的18.62% 降為 18.20%，僅變化 1.5%，表示樣品經過多輪測試後仍維持良好穩定性。TAS 量 測透 過 變溫 條 件掃 描元 件 的電 容 頻率 響 應， 並繪 製 阿瑞尼 斯 圖（Arrhenius plot）後進行擬合，得到缺陷活化能為 45.70 meV，對應之陷阱密度約為 8.84 × 1014 cm−3，屬於較淺層陷阱。DLTS 則是給予元件電壓脈衝，透過電容的瞬態變化觀察到較深的缺陷能階，並成功分離出電子與電洞陷阱，其中電子陷阱能量深度為 511.4 meV，陷阱密度約為 5.86 × 1013 cm−3；電洞陷阱能量深度則為660.4 meV，陷阱密度約為 5.35 × 1013 cm−3。CV 分析利用 Mott-Schottky 擬合法求得內建電壓值約為 1.076 V，並估算摻雜濃度約為 2.03 × 1016 cm−3。進一步透過DLCP 分析於不同頻率與溫度條件下量測，並與 CV 結果比較，可推得樣品缺陷密度於空間中的分布與界面效應。最後，透過利用等效電路模擬阻抗圖譜，成功擷取鈣鈦礦太陽能電池元件的電路元件參數。阻抗分析顯示樣品於低頻區間出現明顯電荷累積與界面極化，對應之界面電容約為 45.7 nF，電荷轉移電阻則約為 14.4 kΩ。綜上所述，本研究建立一套以單一樣品為對象的缺陷量測流程，涵蓋空間、能階深度與頻率響應等。研究結果不僅驗證元件在測試後具有良好穩定性，也提供多項定量參數，對於製程優化與缺陷控制具有重要參考價值。

Perovskite solar cells (PSCs) have attracted widespread attention over the pastdecade due to their high light absorption coefficient, tunable bandgap, and low fabricationtemperature. However, defects formed within the material and at the interfaces stillsignificantly limit the device's stability and performance. Therefore, developing a methodthat can effectively detect and analyze defect characteristics under different temperaturesand frequencies is critical for future optimization of solar cell fabrication and structuraldesign.In this study, a single inverted P-I-N perovskite solar cell was investigated using acombination of electrical measurement techniques and equivalent circuit modeling tosystematically explore its defect characteristics under low-temperature and low-frequency conditions. The measurement techniques used include DLCP (Drive-LevelCapacitance Profiling), CV (Capacitance-Voltage), TAS (Thermal AdmittanceSpectroscopy), and DLTS (Deep Level Transient Spectroscopy), while IS (ImpedanceSpectroscopy) data were used to establish an equivalent circuit model (ECM). Allmeasurements were performed on the same device, with IV tests conducted before andafter the experiments. The reverse-scan power conversion efficiency changed onlyslightly from 18.62% to 18.20%, indicating that the sample maintained good stabilityafter multiple tests.In the TAS measurement, temperature-dependent capacitance-frequency responseswere recorded and fitted using an Arrhenius plot, yielding an activation energy of45.70 meV and a corresponding trap density of approximately 8.84 × 1014 cm−3 ,indicating a shallow trap. DLTS identified deeper trap levels and successfullydistinguished between electron and hole traps. The electron trap energy level was511.4 meV with a density of about 5.86 × 1013 cm−3, while the hole trap level was 660.4 meV with a density of around 5.35 × 1013 cm−3 .The CV analysis used theMott-Schottky method to extract the built-in potential, which was around 1.076 V, andthe estimated doping concentration was about 2.03 × 1016 cm−3 . Further DLCPmeasurements at different frequencies and temperatures, compared with CV results,provided insights into the spatial distribution of defect density and interfacial effects.Finally, an equivalent circuit was used to simulate the impedance spectrum, allowingextraction of key electrical parameters. The impedance analysis showed clear chargeaccumulation and interface polarization in the low-frequency region, with an interfacialcapacitance of about 45.7 nF and a charge transfer resistance of approximately 14.4 kΩ.In summary, this study establishes a defect characterization process based on a singledevice, covering spatial distribution, energy level depth, and frequency response. Theresults confirm the device's stability after testing and provide various quantitativeparameters that are valuable for future process optimization and defect control inperovskite solar cells.