A Cost‐Effective D‐A‐D Type Hole‐Transport Material Enabling 20% Efficiency Inverted Perovskite Solar Cells^†

Abstract

Energy conversion | Donor-acceptor systems | Interfaces | Hole-transport materials | Inverted perovskite solar cells High-performance, cost-effective hole-transport materials (HTMs) are greatly desired for the commercialization of perovskite solar cells (PVSCs). Herein, two new HTMs, TPA-FO and TPA-PDO, are devised and synthesized, which have a donor-acceptor-donor (D-A-D) type molecule design featuring carbonyl group-functionalized arenes as the acceptor (A) units. The carbonyl group at the central core of HTMs can not only tune frontier molecular orbital (FMO) energy levels and surface wettability, but also can enable efficient surface passivation effects, resulting in reduced recombination loss. When employed as HTMs in inverted PVSCs without using dopant, TPA-FO with one carbonyl group yields a high power conversion efficiency (PCE) of 20.24%, which is among the highest values reported in the inverted PVSCs with dopant-free HTMs. More importantly, the facile one-step synthetic process enables a low cost of 30 USD g -1 for TPA-FO, much cheaper than the most studied HTMs used for high-efficiency dopant-free PVSCs. These results demonstrate the potential of D-A-D type molecules with carbonyl group-functionalized arene core in developing the low-cost dopant-free HTMs toward highly efficient PVSCs.

Improving Ultraviolet Stability of Perovskite Solar Cells via Singlet Fission Down‐Conversion†

“…Furthermore, the time‐resolved photoluminescence (TRPL) spectra (Figure 2d) have been also employed to deeply understand the dynamics of charge recombination. [ 53 ] As shown from Table S2, it is observed that TIPS‐PEN incorporated perovskite shows a shorter average lifetime (13.51 ns) compared with the control (35.32 ns), indicating that the photoexcited carriers can be extracted rapidly and thus efficiently inhibit charge carrier recombination. To further elucidate more directly the defect passivation effect of TIPS‐PEN and the more effective charge extraction at the perovskite/HTL interface, the space charge‐limited current (SCLC) measurements are conducted to calculate the trap density and carrier mobility under dark conditions (Figure 2e and Figure S9).…”

Recent advances in dopant-free organic hole-transporting materials for efficient, stable and low-cost perovskite solar cells

“…In 2021, Guo and co-workers prepared two D-A-D type linear small molecule HTMs featuring carbonyl group-functionalized arenes as the acceptor units and MeO-TPA groups as the donor units, denoted as TPA-FO and TPA-PDO. 160 Compared with one carbonyl group functionalized TPA-FO, TPA-PDO containing two carbonyl groups possessed lower hole mobility, stronger wettability harmful for perovskite crystal growth, and weaker interaction with Pb 2+ without the chelation effect. 161 As a result, the dopant-free TPA-FO-based PSCs exhibited an excellent PCE of 20.2%, while the device based on TPA-PDO only gave an inferior PCE of 17.0%.…”

Recent Progresses on Dopant‐Free Organic Hole Transport Materials toward Efficient and Stable Perovskite Solar Cells†

“…Also on p‐i‐n PSCs, Guo's group designed and synthesized two new HTMs ( TPA‐FO and TPA‐PDO ) with carbonyl as the central atom. [ 33 ] The carbonyl groups of TPA‐FO and TPA‐PDO could not only improve the surface wettability and adjust the frontier molecular orbital energy level, but also achieve effective surface passivation effect to reduce the recombination loss. The dopant‐free TPA‐FO with one carbonyl group produced a high PCE of 20.24%, while its cost was as low as $30 g –1 by a simple one‐step synthesis process.…”