三種基于二噻吩酰亞胺（BTI）的新型有機(jī)小分子——BTI-MN-b4（1）、BTI-MN-b8（2）和BTI-MN-b16（3），它們各自擁有獨(dú)特的烷基側(cè)鏈，并被精心設(shè)計(jì)以用作錫基鈣鈦礦太陽(yáng)能電池（TPSCs）中NiOx薄膜上的自組裝單層（SAMs）。這些SAM分子在構(gòu)建高質(zhì)量的TPSC鈣鈦礦層中發(fā)揮著不可或缺的作用。

NYCU 刁維光（Eric Wei-Guang Diau）教授及其團(tuán)隊(duì)，通過(guò)密度泛函理論（DFT）計(jì)算，深入剖析了這些分子的結(jié)構(gòu)特性。具體而言，三苯胺基團(tuán)巧妙地連接在BTI核心的一側(cè)，從而促進(jìn)了電荷向鈣鈦礦層的有效傳輸；而氰基與噻吩單元?jiǎng)t形成了共軛結(jié)構(gòu)，連接在BTI核心的另一側(cè)，作為錨定基團(tuán)與NiOx/ITO表面緊密結(jié)合，形成了強(qiáng)烈的相互作用。此外，NiOx在改善ITO基底性能方面展現(xiàn)出了顯著的效果，使得BTI-MN-b4（1）、BTI-MN-b8（2）和BTI-MN-b16（3）能夠均勻且穩(wěn)定地形成SAMs。尤為重要的是，刁維光教授團(tuán)隊(duì)成功解析了BTI-MN-b8（2）的單晶結(jié)構(gòu)，這一重大發(fā)現(xiàn)不僅進(jìn)一步驗(yàn)證了其設(shè)計(jì)思路的合理性，也為后續(xù)的性能測(cè)試奠定了堅(jiān)實(shí)的理論基礎(chǔ)。

在性能測(cè)試環(huán)節(jié)，刁維光教授團(tuán)隊(duì)將BTI-MN-b8（2）與NiOx結(jié)合應(yīng)用于TPSCs，使其**光電轉(zhuǎn)換效率（PCE）高達(dá)8.6%。這一效率顯著優(yōu)于僅使用NiOx作為空穴傳輸材料（HTM）時(shí)的4.0%的PCE。更為令人振奮的是，采用NiOx/BTI-MN-b8配置的TPSC器件在歷經(jīng)3600小時(shí)的長(zhǎng)期穩(wěn)定性測(cè)試后，仍保持了約80%的初始效率。這一**的長(zhǎng)期穩(wěn)定性表現(xiàn)，無(wú)疑為TPSCs在實(shí)際應(yīng)用中的可靠性提供了強(qiáng)有力的支撐。

為了全面而深入地評(píng)估這些SAM分子的性能，刁維光教授團(tuán)隊(duì)采用了多種表征手段，包括熱分析、光學(xué)分析、電化學(xué)分析和形態(tài)分析等。這些表征手段不僅詳盡地揭示了NiOx/SAM/鈣鈦礦薄膜的光電和光伏特性，還直觀地展示了相應(yīng)器件的**性能。特別值得一提的是，BTI-MN-b8（2）分子與NiOx的結(jié)合展現(xiàn)出了**的光電轉(zhuǎn)換效率和長(zhǎng)期穩(wěn)定性。刁維光教授團(tuán)隊(duì)的研究成果不僅驗(yàn)證了其分子設(shè)計(jì)策略的**性，更為TPSC技術(shù)的未來(lái)發(fā)展帶來(lái)了革命性的突破。這一研究不僅為采用兩步法制備技術(shù)的TPSC技術(shù)發(fā)展開辟了新的方向，還為實(shí)現(xiàn)更高的性能和穩(wěn)定性提供了切實(shí)可行的創(chuàng)新方法和思路，對(duì)TPSCs領(lǐng)域的實(shí)際應(yīng)用和理論研究都具有重要意義。

Figure 1. Chemical structures of the (a) reported SAMs for Pb-PSCs and TPSCs; (b) BTI-based small molecule and polymers for OTFTs, OPVs, and PSCs; and (c) BTI-based SAM molecules 1–3 for TPSCs studied in this work.

Scheme 1. Synthetic Route to BTI-Based SAM Molecules 1–3

Figure 2. (a) UV–vis absorption spectra; (b) DPV curves; and (c) DFT-derived energy levels and electrostatic surface potential (ESP) mapping of BTI-MN compounds.

Figure 3. Single crystal structure of compound 2. (a) Top view of BTI-MN-b8 molecule with intramolecular interactions in a space-filling model; (b) top view of BTI-MN-b8 molecule with various twisted angles in stick model; (c, d) front views of BTI-MN-b8 molecule the space-filling and stick models, respectively; and (e) expected packing pattern of SAM on NiOx/ITO substrate (front view).

Figure 4. (a–d) Contact angle of SnI2 precursor on NiOx and NiOx/SAM surfaces. (e–h) SEM, (i–l) AFM, and (m–p) XPS of tin perovskites made on NiOx and NiOx/SAM surfaces.

Figure 5. (a) XRD patterns of tin perovskites on NiOx with various SAMs, as specified; (b) PL decay profiles obtained using TCSPC; (c) SCLC measurements of tin perovskites on NiOx with the various indicated SAMs; (d) J–V characteristic curves; (e) IPCE and (f) UV–vis absorption and PL spectroscopy of tin perovskites on NiOx with various SAMs, as specified; (g) EIS Nyquist plots for devices composed of tin perovskites deposited on NiOx with various SAMs, as specified; (h) energy-level diagram; and (i) long-term stability of devices containing NiOx with various SAMs, as specified. The highest-performing device, NiOx/BTI-MN-b8, achieved a PCE of 8.6%.

文獻(xiàn)信息：

Bithiophene Imide-Based Self-Assembled Monolayers (SAMs) on NiOx for High-Performance Tin Perovskite Solar Cells Fabricated Using a Two-Step Approach

• Arulmozhi Velusamy，Chun-Hsiao Kuan，Tsung-Chun Lin，Yun-Sheng Shih，Cheng-Liang Liu，De-You Zeng，Yu-Gi Li，Yu-Hao Wang，Xianyuan Jiang，Ming，Chou Chen，Eric Wei-Guang Diau

• https://pubs.acs.org/doi/10.1021/acsami.4c15688

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