Enhancement of Efficiency of Perovskite Solar Cells with Hole-Selective Layers of Rationally Designed Thiazolo[5,4-<i>d</i>]thiazole Derivatives
Asta Dabulienė, Zhong‐En Shi, Karolis Leitonas, Chien‐Yu Lung, Dmytro Volyniuk, Khushdeep Kaur, V.E. Matulis, Dmitry Lyakhov, Dominik L. Michels, Chih‐Ping Chen, Juozas V. Gražulevičius
Abstract
High Resolution Image Download MS PowerPoint Slide We introduce thiazolo[5,4- d ]thiazole (TT)-based derivatives featuring carbazole, phenothiazine, or triphenylamine donor units as hole-selective materials to enhance the performance of wide-bandgap perovskite solar cells (PSCs). The optoelectronic properties of the materials underwent thorough evaluation and were substantially fine-tuned through deliberate molecular design. Time-of-flight hole mobility TTs ranged from 4.33 × 10 –5 to 1.63 × 10 –3 cm 2 V –1 s –1 (at an electric field of 1.6 × 10 5 V cm –1 ). Their ionization potentials ranged from −4.93 to −5.59 eV. Using density functional theory (DFT) calculations, it has been demonstrated that S0 → S1 transitions in TTs with carbazolyl or ditert -butyl-phenothiazinyl substituents are characterized by local excitation (LE). Mixed intramolecular charge transfer (ICT) and LE occurred for compounds containing ditert -butyl carbazolyl-, dimethoxy carbazolyl-, or alkoxy-substituted triphenylamino donor moieties. The selected derivatives of TT were used for the preparation of hole-selective layers (HSL) in PSC with the structure of glass/ITO/HSLs/Cs 0.18 FA 0.82 Pb(I 0.8 Br 0.2 ) 3 /PEAI/PC 61 BM/BCP/Ag. The alkoxy-substituted triphenylamino containing TT ( TTP-DPA ) has been demonstrated to be an effective material for HSL. Its layer also functioned well as an interlayer, improving the surface of control HSL_2PACz (i.e., reducing the surface energy of 2PACz from 66.9 to 52.4 mN m –1 ), thus enabling precise control over perovskite growth energy level alignment and carrier extraction/transportation at the hole-selecting contact of PSCs. 2PACz/ TTP-DPA- based devices showed an optimized performance of 19.1 and 37.0% under 1-sun and 3000 K LED (1000 lx) illuminations, respectively. These values represent improvements over those achieved by bare 2PACz-based devices, which attained efficiencies of 17.4 and 32.2%, respectively. These findings highlight the promising potential of TTs for the enhancement of the efficiencies of PSCs.