| 摘要: | 鈣鈦礦太陽能電池(Perovskite solar cells，簡稱PSCs)的鈣鈦礦膜與電洞傳遞層(Hole transport layer，簡稱HTL)界面的缺陷會導致鈣鈦礦膜吸光產生的電子電洞無法順利傳遞出去，而且鈣鈦礦膜的晶界容易被水降解，使PSCs元件的光電轉換效率和穩定性變差。本研究透過在反溶劑氯苯(Chlorobenzene，簡稱CB)中添加Bicyclopentadithiophene衍生物(簡稱IN-BCDT系列)，共有6個分子。分別是IN-BCDT-8及在IN-BCDT-8的Indene分子上引入Cl、Br而形成INCl-BCDT-8和INBr-BCDT-8；再將IN-BCDT-8、INCl-BCDT-8和INBr-BCDT-8的正辛基改為2-乙基己基，形成IN-BCDT-b8和INCl-BCDT-b8和INBr-BCDT-b8。以這六個材料所修飾的鈣鈦礦膜分別稱為Psk@8、Psk@Cl-8、Psk@Br-8、Psk@b8、Psk@Cl-b8和Psk@Br-b8，未添加修飾劑的鈣鈦礦膜稱為Psk@CB。其中，以Psk@Cl-b8和Psk@Br-b8為吸收層所組裝的元件的光電轉換效率最高分別可達20.51%和21.69%，比以Psk@CB為吸收層所組裝的元件的19.02%增加了8%和14%。從FT-IR穿透光譜可以看到INCl-BCDT-b8的氰基和羰基的訊號峰在添加PbI2後分別往低波數位移11 cm-1和12 cm-1，而INBr-BCDT-b8的氰基和羰基的訊號峰則在添加PbI2後都往低波數位移28 cm-1，表示這兩個分子的氰基和羰基將其上未鍵結的電子與鈣鈦礦膜中配位未飽和的Pb2+配位，而且INBr-BCDT-b8可以與更多的未鍵結Pb2+配位，因此SEM表面形貌看到Psk@Br-b8晶粒最大且平整，增加所組裝的PSC元件的Voc值(從1.03 V增加至1.10 V)和FF值(從73%提高至77%)。由於INBr-BCDT-b8中噻吩硫上的未定域電子增加鈣鈦礦膜的導電度(從1.69 x 10-2 mS cm-1增大至2.32 x 10-2 mS cm-1)，Psk@Br-b8上沉積Spiro-OMeTAD膜的TRPL圖可以看到激子半生期較Psk@CB短，表示INBr-BCDT-b8可以幫助電洞更快地從鈣鈦礦膜傳遞至電洞傳遞層。而且分子上的烷基可以增加鈣鈦礦膜的疏水性，Psk@Br-b8的水接觸角加至86.5 o比Psk@CB的44.9 o大。使所組裝Psc元件的長時間穩定性較好，以Psk@Br-b8所組裝的元件在手套箱未封裝經80天後仍可維持原效率的91%；相同條件下，以Psk@CB所組裝的元件僅可維持原效率的77%。;The interface defects of perovskite solar cells (PSCs) will cause serious problems, such as the carriers trapping and absorber layer degrading by water, which deteriorate the power conversion efficiency and stability of the PSCs. In this study, by adding bicyclopentadithiophene derivatives (abbreviated as IN-BCDT series) to the chlorobenzene (CB) anti-solvent in the processes for preparing perovskite layer. IN-BCDT series contain 6 molecules：IN-BCDT-8, INCl-BCDT-8, INBr-BCDT-8, IN-BCDT-b8, INCl-BCDT-b8, and INBr-BCDT-b8. The perovskite films prepared by CB containing IN-BCDT series are named as Psk@8, Psk@Cl-8, Psk@Br-8, Psk@b8, Psk@Cl-b8, and Psk@Br-b8, respectively. Perovskite films fabricated form pure CB anti-solvent was called Psk@CB. The power conversion efficiency of the PSCs based on Psk@Cl-b8 and Psk@Br-b8 absorbers reach the highest values of 20.51% and 21.69%, respectively, which is higher than that (19.02%) of PSCs assembled with Psk@CB absorber (8% and 14% increasing). FT-IR transmission spectra show the absorption peaks of the cyano group and carbonyl group of INCl-BCDT-b8 shifted to lower wavenumbers (11 cm-1 and 12 cm-1 lower) when it was mixed with PbI2. When INBr-BCDT-b8 was mixed with PbI2, the absorption peaks of cyano and carbonyl groups red-shifted even bigger (28 cm-1), indicating that both cyano and carbonyl group of these two molecules can coordinate with uncoordinate Pb2+ in perovskite and the bonding between INBr-BCDT-b8 Pb2+ is stronger. SEM surface morphology shows that Psk@Br-b8 is a flat film with the largest size, which increases the Voc of the corresponding PSC (from 1.03 V for PSC based on Psk@CB absorber to 1.10 V) and FF value (from 73% to 77%) as well as the conductivity (from 1.69 x 10-2 mS cm-1 to 2.32 x 10-2 mS cm-1) of the provekite films. The TRPL data of the Spiro-OMeTAD/ Psk@Br (Spiro-OMeTAD film deposited on Psk@Br) show the exciton half-lifes is shorter than that of Spiro-OMeTAD/Psk@CB, indicating that INBr-BCDT-b8 can extract holes from perovskite film and transport to anode faster. Moreover, the alkyl group on the molecule can increase the hydrophobicity of the perovskite film, the water contact angle of Psk@Br-b8 is 86.5o which is larger than that (44.9o) of Psk@CB. The PSC based on Psk@Br-b8 absorber can maintain 91% of its original efficiency after 80 days in the glove box without packaging. Under the same conditions, PSC assembled with Psk@CB absorber losts 23% of the original efficiency. |
