Hole‐Transporting Molecules with Tetrabenzo[a,c,g,i]carbazole Core for Highly Efficient Perovskite Solar Cells

Abstract

Hole‐transporting materials (HTMs) are the key component of perovskite solar cells (PSCs) for the role of extracting photogenerated holes, as well as the charge transporting between perovskite layer and metal electrode. Herein, with the aim to enhance the hole mobility by compact molecular packing, the modification of HTMs focuses on the extension of conjugated cores from the commonly used carbazole (Cz) to tetrabenzo[a,c,g,i]carbazole (TBC). Because of the closely cofacial stacking mode of the TBC core with an X‐type symmetric structure, the resultant TBC‐2,7,11,16‐tetra‐diphenylamine (TD) can achieve a hole mobility of 6.6 × 10−4 cm2 V−1 s−1 and the corresponding conversion efficiency of 20.52%, higher than that of the analogue Cz‐TD (18.34%).

Ionization of hole-transporting materials as a method for improving the photovoltaic performance of perovskite solar cells

“…47,73,74 The symmetric X-type arrangement can improve backbone p-p stacking interactions, which is benecial in achieving high hole mobility. 75 Inverted PSCs also have the HTM sandwiched between the ITO and absorber layers. It would be advantageous to build an HTM that, in conjunction with effective hole transport, can promote the formation of a good perovskite layer and improve PSC efficiency.…”

Starburst Carbazole Derivatives as Efficient Hole Transporting Materials for Perovskite Solar Cells

“…[12,[18][19][20][21][22][23][24][25] Carbazole (Cbz) moiety has been widely used as a building block in HTMs for PSCs due to its low cost, good charge transporting ability, chemical stability, and facile modification with a wide variety of functional groups. [26][27][28][29][30][31][32][33][34][35][36][37][38][39] In addition, the carbazole-based HTMs have the advantage in that they do not contain methoxy substituents, such as those found on spiro-OMeTAD, and could increase the hydrophilicity of the HTM layer, thus affecting the device stability. [40] Carbazole moiety can act as the core unit with a planar structure [26][27][28][29][30][31][32][33] and/or periphery moiety with the hole transporting function.…”

“…[26][27][28][29][30][31][32][33][34][35][36][37][38][39] In addition, the carbazole-based HTMs have the advantage in that they do not contain methoxy substituents, such as those found on spiro-OMeTAD, and could increase the hydrophilicity of the HTM layer, thus affecting the device stability. [40] Carbazole moiety can act as the core unit with a planar structure [26][27][28][29][30][31][32][33] and/or periphery moiety with the hole transporting function. [34][35][36][37][38][39][40][41] Morphological stability of the HTMs is an important factor to consider, especially at elevated temperatures at which real-world devices have to operate.…”

“…[ 26–39 ] In addition, the carbazole‐based HTMs have the advantage in that they do not contain methoxy substituents, such as those found on spiro‐OMeTAD, and could increase the hydrophilicity of the HTM layer, thus affecting the device stability. [ 40 ] Carbazole moiety can act as the core unit with a planar structure [ 26–33 ] and/or periphery moiety with the hole transporting function. [ 34–41 ]…”