Branched methoxydiphenylamine-substituted fluorene derivatives as hole transporting materials for high-performance perovskite solar cells

Abstract

Small-molecule fluorene HTMs were synthesized and tested in perovskite solar cell, PCE of up to 19.96% was reached.

Interfacial Engineering of Perovskite Solar Cells by Employing a Hydrophobic Copper Phthalocyanine Derivative as Hole‐Transporting Material with Improved Performance and Stability

“…[7,8] Thus, aH TM with as uitablee nergy level would alleviate the interfacial energy barriers and minimize undesired recombination losses at the interfaces, therebye nhancingt he overall photovoltaic performance. HTMs take on the role of extracting and collecting the photo-generated holes from the perovskite absorber.…”

High‐Efficiency Perovskite Solar Cells Using Molecularly Engineered, Thiophene‐Rich, Hole‐Transporting Materials: Influence of Alkyl Chain Length on Power Conversion Efficiency

“…[18][19][20][21][22][23][24][25][26] An alternative chemical approach for designing high efficient HTMs is based on polycyclic aromatics as a central core, such as pentacene, [27] triazatruxene, [28] thiolated nanographene [29] or benzotrithiophene, [30] endowed with arylamines derivatives. These -conjugated structures show excellent holetransporting properties due to the stacking of the planar structure through intramolecular - interactions, which lead to excellent power conversion efficiencies.…”

Low‐Cost Perovskite Solar Cells Employing Dimethoxydiphenylamine‐Substituted Bistricyclic Aromatic Enes as Hole Transport Materials

“…To date, molecular spiro‐type HTMs spiro‐OMeTAD [2,2′,7,7′‐tetrakis‐( N , N ‐di‐4‐methoxyphenylamino)‐9,9′‐spirobifluorene], FDT {2′,7′‐bis[bis(4‐methoxyphenyl)amino]spiro[cyclopenta(2,1‐b:3,4‐b′)dithiophene‐4,9′‐fluorene]}, and DDOF {2,2’,7,7′‐tetrakis‐( N , N ′‐di‐4‐methoxyphenylamine)dispiro‐[fluorene‐9,4′‐dithieno(3,2‐c:2′,3′‐e)oxepine‐6′,9′′‐fluorene]} reached the highest reported values over 19 % along with various other small‐molecule HTMs based on paracyclophane, truxene, benzotrithiophene, fluorene, carbazole, triazatruxene, anthratetrathiophene, phthalocyanine, indoloindole, and phenothiazine, successfully reaching comparably high photovoltaic performance. However, there are still only very few examples with a particular emphasis on low‐cost and highly efficient molecular HTMs such as spiroxanthene‐, fluorene‐, carbazole‐, and bifluorene‐based compounds including recently reported KR216 based on bifluorenylidene, and obtained by straightforward strategies showing that proper molecular engineering may be very fruitful toward low‐cost commercial solar cell application. The aforementioned synthetic flexibility and suitability for hole‐transport properties sparked us to continue exploring this class of compounds.…”

“…To date, molecular spiro-typeH TMs spiro-OMeTAD [2,2',7,7'-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene], [13,14] FDT {2',7'-bis[bis(4-methoxyphenyl)amino]spiro[cyclopenta(2,1-b:3,4-b')dithiophene-4,9'-fluorene]}, [15] and DDOF {2,2',7,7'-tetrakis-(N,N'-di-4-methoxyphenylamine)dispiro-[fluorene-9,4'-dithieno(3,2-c:2',3'-e)oxepine-6',9''fluorene]} [16] reached the highest reported values over 19 % along with variouso ther small-molecule HTMs based on paracyclophane, [17] truxene, [18] benzotrithiophene, [19,20] fluorene, [21,22] carbazole, [23][24][25] triazatruxene, [26,27] anthratetrathiophene, [28] phthalocyanine, [29,30] indoloindole, [31] and phenothiazine, [32] successfully reaching comparably high photovoltaic performance. However,t here are still only very few examples with ap articular emphasis on low-costa nd highly efficient molecular HTMs such as spiroxanthene-, [33,35] fluorene-, [36] carbazole-, [37,38] and bifluorene-based [39] compounds includingr ecently reported The synthesis, characterization and photovoltaic performance of series of novel molecular hole transport materials (HTMs) based on bistricyclic aromatic enes (BAEs) are presented. The new derivatives were obtained following as imple and straightforwardp rocedure from inexpensive starting reagents mimicking the synthetically challenging 9,9'-spirobifluorene moiety of the well-studied spiro-OMeTAD.…”