錫鉛混合鈣鈦礦(TLPSK)因其能隙(~1.2eV)小於純錫鈣鈦礦和純鉛鈣鈦礦，能夠作為全鈣鈦礦堆疊型太陽能電池的下層電池的吸收層而受到關注。在製備錫鉛混合鈣鈦礦膜時，由於錫鈣鈦礦的結晶速度比鉛鈣鈦礦快，導致膜的品質不佳且膜中的錫與鉛離子分布不均勻，影響鈣鈦礦膜的吸光。另外，二價錫容易被氧化成四價錫而導致所組裝的太陽能電池的光電轉換效率低。為了解決上述缺點，本研究選用了不同胺基取代位置的2-甲基吡啶(amino-2-methylpyridine)的異構物(以下稱xA2M，其中x是amino group位置)作為鈣鈦礦的添加劑，利用上述分子上的胺基或吡啶上氮原子的孤對電子和鈣鈦礦組成中的錫、鉛鈣鈦礦的前驅物產生交互作用，藉此使二者的結晶速度趨於一致，以製備高品質錫鉛混合鈣鈦礦膜。FT-IR光譜中顯示，這些xA2M和錫離子的作用力皆比和鉛離子的作用力大，且與錫的作用力由大至小依序為4A2M > 6A2M > 5A2M > 3A2M，而DLS結果顯示，添加xA2M的錫鉛鈣鈦礦前驅溶液的膠體大小皆有得到不同程度的控制，其中以添加5A2M的錫鉛鈣鈦礦前驅溶液的膠體大小的分佈最為集中。首先，藉由Top view SEM圖比較未添加和添加了這四種分子的鈣鈦礦膜的晶粒大小的分布情況，發現添加5A2M的鈣鈦礦膜的晶粒幾乎集中分布於200 nm到500 nm之間，而未添加與添加了另外三種分子的鈣鈦礦膜的晶粒雖然也有大量分布在200 nm到500 nm之間，但是有較多小於200 nm和大於500 nm的晶粒產生，此結果說明了5A2M與錫、鉛離子之間的交互作用能夠最有效地調控錫、鉛鈣鈦礦的結晶速度，使晶粒的成長速度較一致，晶粒尺寸較相近，而其餘三者與金屬離子之間作用力的大小無法有效調控錫鉛鈣鈦礦的結晶速度，尺寸差異較大。XRD圖中也顯示出添加5A2M的鈣鈦礦膜其(100)晶面的繞射峰強度最高，意味著鈣鈦礦的晶格的排列最為規整，綜合以上數據可知，xA2M與錫、鉛離子的作用力要適中才能有效地去平衡錫鈣鈦礦和鉛鈣鈦礦的結晶速度並調控結晶過程，才能製備出高光伏性能的鈣鈦礦膜。未添加的鈣鈦礦膜作為吸光層所組裝的太陽能電池的光電轉換效率為19.33%，添加3A2M、4A2M、5A2M或6A2M的鈣鈦礦膜作為吸光層所組裝的太陽能電池的光電轉換效率分別為20.82%、19.89%、21.23%和19.37%。將未封裝的元件放置於室溫的氮氣環境中1080小時後，未添加和分別添加3A2M、4A2M、5A2M或6A2M的鈣鈦礦膜作為吸光層所組裝的元件光電轉換效率分別維持原本的77%、81%、80%、86%和77%。;Tin–lead mixed perovskites (TLPSKs) have emerged as highly promising low-bandgap (~1.2 eV) absorbers for all-perovskite tandem solar cells. However， the development is inherently hampered by the mismatched crystallization rates between tin and lead perovskites， which typically induces severe compositional heterogeneity， poor film morphology， and detrimental oxidation of Sn²⁺ to Sn⁴⁺.Herein， this study overcomes these problems by introducing amino-2-methylpyridine isomers (xA2M) as multifunctional additives. By leveraging the lone-pair electrons from either the amino groups or the pyridine nitrogen atoms， these molecular variants strategically coordinate with both tin and lead precursors to synchronizing their distinct crystallization pathways. FT-IR spectroscopy reveals that the xA2M isomers possess a fundamentally stronger affinity toward Sn than Pb， with the Sn-coordination strength decreasing in the order of 4A2M > 6A2M > 5A2M > 3A2M. Top-view SEM images unveils that this interaction hierarchy directly dictates film morphology. Specifically， 5A2M yields an exceptionally uniform film with grain sizes tightly confined within 200 to 500 nm. In contrast， both the pristine films and films modified with the other three isomers exhibit a disordered， bimodal grain distribution with abundant sub-200 nm and oversized (>500 nm) clusters. This stark disparity underscores that 5A2M offers a precisely tailored chemical environment to balance crystal growth. Concurrently， XRD analysis shows that the 5A2M-engineered perovskite exhibits the highest diffraction intensity along the (100) lattice plane， implying a superior， highly oriented crystalline order. Collectively， our findings establish a fundamental design rule for perovskite additives: the coordination strength between organic ligands and metal cations must be finely optimized—rather than maximized—to effectively homogenize the crystallization kinetics. Driven by this structural refinement， the solar cells leveraging the 5A2M-modified absorber deliver a superior power conversion efficiency (PCE) of 21.23%， substantially outperforming the control device (19.33%) and those with 3A2M (20.82%)， 4A2M (19.89%)， and 6A2M (19.37%). Furthermore， unencapsulated 5A2M devices exhibit exceptional long-term durability， retaining 86% of their initial efficiency after 1080 hours of aging in a room-temperature nitrogen environment， markedly surpassing the 77% retention of the pristine control cell.
