錫鈣鈦礦(簡稱:TPSK)太陽能電池是將原鉛鈣鈦礦太陽能電池的主動層中心鉛金屬以錫取代，因著TPSK有較鉛鈣鈦礦更接近Shockley–Queisser limit (S–Q limit)中最佳光電轉換效率所需具備的吸光層能隙(1.34 eV)，因此深受科學家重視；至今TPSK太陽能電池之光電轉換效率已達13%，然而TPSK膜中若有Sn4+ 存在會使TPSK因晶格缺陷而有電荷再結合、吸光能力不佳等問題，使所組裝之元件有不好的光伏表現。因此本研究將不同的金屬(Mg/Fe/Co/Ni/Zn/Sn)粉末做為還原劑添加入TPSK前驅溶液中，來還原前驅溶液中的Sn4+成Sn2+ (Sn4+ + 2?e? ? Sn2+ E0: +0.15 V)。實驗結果顯示，以用鎳金屬(Ni ? Ni2+ + 2?e? E0: +0.25 V)來還原前驅溶液能製備出高結晶度、平整且吸光能力佳的TPSK膜，以此高品質TPSK膜作為吸收層之反式TPSK太陽能電池元件有最高的光電流密度(22.24 mA/cm2 )，及光電轉換效率(8.56%)。其中，添加鐵、鈷、鎳、鋅、錫等金屬皆能使TPSK前驅溶液中的Sn4+還原成Sn2+，同時又能避免Sn4+過度還原成Sn0 (2Sn2+ ? Sn0 + Sn4+ E0: -0.28 V)。以上述五種金屬還原的TPSK前驅溶液所製備的膜比由未添加金屬還原劑之溶液所製的膜有較高的吸光度，由光致螢光(PL)及時間解析螢光(TRPL)光譜圖可看見經還原後之前驅溶液所製備的TPSK膜激子較不易淬熄，所製得之錫鈣鈦礦膜缺陷較少，因此所組裝之錫鈣鈦礦太陽能電池有較高的光電轉換效率；然而鎂金屬因其過強(Mg ? Mg2+ + 2?e? E0: +2.93 V)的還原力會將Sn2+直接還原成Sn0，因此以添加鎂的TPSK前驅溶液所製備的膜為吸光層之元件的效率(0.5%)很低。;Tin perovskite (TPSK) solar cell (T-PSC) is a cell used tin to replace the high toxic lead in the active layer of perovskite sola cell (PSC). TPSK with a band gap close to the ideal energy gap (~1.34 eV) in Shockley–Queisser limit (S–Q limit) causes a great attention in solar cell community. To date, the photoelectric conversion efficiency of TPSK has reached 13 %. However, the presence of Sn4+ in the TPSK film will causethe lattice defects, charge recombination, and poor light absorption, resulting in poor photovoltaic performance when applied in T-PSC.In this study, various metal (Mg/Fe/Co/Ni/Zn/Sn) powders were added to the TPSK precursor solution to reduce Sn4+ to Sn2+ (Sn4+ + 2?e? ? Sn2+ E0: +0.15 V). The results show that nickel (Ni ? Ni2+ + 2?e? E0: +0.25 V) is the most suitable to reduce Sn4+ in recursor solution to prepare high crystallinity, flatness, and good absorption Ni-TPSK film. The T-PSCbased on high-quality Ni-TPSK film has the highest photocurrent density (22.24 mA/cm2) and photoelectric conversion efficiency (8.56 %) vs 5.12% for that based un-reduced TPSK film. Photoluminescence (PL) and Time-Resolved Photoluminescence (TRPL) spectrum revealed that the excitons of the reduced TPSK film are less likely to be quenched suggested that reduced TPSK film has fewer defects. Therefore, the assembled tin perovskite solar cell has a higher photoelectric conversion efficiency. However, magnesium will over reduce Sn4+ to Sn0 due to its high reduction potential (Mg ? Mg2+ + 2?e? E0: +2.93 V). Thus, the efficiency of T-PSC based on Mg reduced tin perovskite (Mg-TPSK) absorber has very low efficiency (0.5%).
