Efficient Inverted Perovskite Solar Cells Enabled by Dopant-Free Hole-Transporting Materials Based on Dibenzofulvene-Bridged Indacenodithiophene Core Attaching Varying Alkyl Chains

Abstract

Inspired by the structural advantages of spiro-OMeTAD, which is the most commonly used hole-transporting material (HTM), two rationally designed HTMs with butterfly-shaped triarylamine groups based on dibenzofulvene-bridged indacenodithiophene (IDT) core (attaching hexyl and octyl chains) have been synthesized, namely, IT-C6 and IT-C8, respectively. Shorter alkyl-chain-based IT-C6 exhibits a marked increase in glass-transition temperature (T g ) of 105 °C, whereas IT-C8 shows a T g of 95 °C. Moreover, it is demonstrated that IT-C6 exhibits a higher hole-transporting mobility, more suitable band energy alignment, better interfacial contact, and passivation effect. The inverted devices of employed HTM based on IT-C6 obtained a champion PCE of 18.34% with a remarkable fill factor (FF) of 82.32%, whereas the IT-C8-based device delivered an inferior PCE of 16.94% with an FF up to 81.20%. Both HTMs embodied inverted devices present high FF values greater than 81%, which are among the highest reported values of small molecular HTM-based PSCs. This work reveals that cutting off the symmetrical spiro-core and subsequently combining IDT (attaching tailored alkyl chains) with the spiro-linkage fluorine to construct the orthogonal molecular conformation is a significant principle for the design of promising dopant-free HTMs.

Quantum Dot Interface-Mediated CsPbIBr2 Film Growth and Passivation for Efficient Carbon-Based Solar Cells

“…Hence, the trap-state density of the PSCs is significantly decreased from 3.49 × 10 16 (pristine) to 2.92 × 10 16 cm –3 (with PbS QDs). The suppressed charge recombination was also confirmed from a smaller ideality factor of 1.46 KT / e for the target device compared to that of 1.76 KT / e for the control, as demonstrated from the light intensity dependence of V oc of the two cells (Figure f). , The low trap density and improved charge transport indicate a high crystallization quality in the modified perovskite film, which is also predicted from the DFT calculation on lattice-matched epitaxial growth via interfacial PbS QD media.…”

Dopant‐Free Phthalocyanine Hole Conductor with Thermal‐Induced Holistic Passivation for Stable Perovskite Solar Cells with 23% Efficiency

“…The differential scanning calorimetry (DSC) curve (Figure S6b, Supporting Information) exhibited a much higher glass‐transition temperature ( T g ) of 223 °C than that of spiro‐OMeTAD ( T g = 125 °C). [ 28 ] Similarly, a second transition at 263 °C ascribed to a mesophase–isotropic phase transition was observed. [ 26 ] The above results verified the outstanding stability of the amorphous state of the SMe‐TPA‐CuPc HTM, which is beneficial for improving the thermal stability of the corresponding PSC.…”

Boosting the performance and stability of inverted perovskite solar cells by using a carbolong derivative to modulate the cathode interface

“…20 All the layers except for the electrodes are solution processed, which is lowcost and straightforward. 21 The perovskite composition is (CsPbI 3 ) 0.05 [(FAPbI 3 ) 0.9 (MAPbBr 3 ) 0.1 ], whose related characterization including surface SEM morphology (Fig. S5, ESI †), film XRD (Fig.…”