Investigation of charge-transporting properties of dibenzothiophene-based derivatives as dopant-free hole-transporting materials of perovskite solar cells
Dmytro Volyniuk a, Ranush Durgaryan a, Jurate Simokaitiene a, Oleksandr Bezvikonnyi a, Yan Danyliv a, Kai Lin Woon b, Juozas Vidas Grazulevicius a
a Department of Polymer Chemistry and Technology, Kaunas University of Technology, Baršausko Str. 59, LT, 51423, Kaunas, Lithuania
b Low Dimensional Materials, Department of Physics, University of Malaya, Jalan Profesor Diraja Ungku Aziz, Kuala Lumpur, Malaysia
nanoGe Fall Meeting
Proceedings of Materials for Sustainable Development Conference (MAT-SUS) (NFM22)
#OPTONEXT - Next Gen Semiconductors for Optoelectronics
Barcelona, Spain, 2022 October 24th - 28th
Organizers: Paul Shaw and Mike Hambsch
Poster, Dmytro Volyniuk, 333
Publication date: 11th July 2022

It is widely known that a supporting hole transporting material is used in a perovskite solar cell (PSCs) to improve the device efficiency. The conventional material is 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (spiro-OMeTAD) has several drawbacks. One of them the requirement of hydrophilic additives which can enhance its conductivity and mobility. With the purpose to overcome those drawbacks, we developed three new derivatives of dibenzothiophene and conducted a comprehensive study of their properties including absorption, photoluminescence, photoemission, cyclic voltammetry, charge mobility and molecular dynamics (MD) [1]. The charge extraction by linearly increasing voltage (CELIV) and time-of-flight (TOF) techniques were employed to measure the hole mobility of dibenzothiophene derivatives as a function of electric field and temperature. We observed that the  hole mobility has no major impact on the performance of the solar cell. Based upon the Gaussian disorder model the hole mobility the parameters of diagonal and off-diagonal (positional) disorder were extracted. In parallel, the parameters for positional disorder (interstice, orientational, and torsional disorder) were determined via MD studies. The results of the mobility measurements and MD studies are mutually consistent regarding positional disorder. The dopant-free PSCs with one of the synthesized derivatives dibenzothiophene exhibited efficiency slightly above of 20% which was much higher than that of dopant-free spiro-OMeTAD-based reference device. This result is consistent with both appropriate hole density dynamics characterized by “effective” hole recombination rate of 11.8 ms-1 and hole-transporting properties with hole mobility of 9.45×10-4 cm2/Vs of the derivative of dibenzothiophene.

This project has received funding in the frame of the program SMART-ER Seed Project (“T-i-PSCer” No V22/02/36).

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