Designed p-type graphene quantum dots to heal interface charge transfer in Sn-Pb perovskite solar cells

Liu

Advanced Energy Materials

et al. 2023

Perovskite solar cells (PSCs) and organic solar cells (OSCs) face device efficiency losses and instability challenges with existing hole transport materials (HTMs). The development of new universal HTMs is in great demand to promote their practical applications. Herein, a versatile self‐assembled molecule (SAM) based HTM is designed for record‐high efficiency wide‐bandgap (WBG, Eg >1.75 eV) PSCs, all‐perovskite tandem solar cells (TSCs) and OSCs. The SAM exhibits high transmission and a lower‐lying energy level, enabling enhanced interfacial charge transfer and suppressed non‐radiative recombination losses. SAM based WBG PSCs deliver a maximum power conversion efficiency (PCE) of 18.63% with over 90% efficiency retention after 250 h continuous work. By stacking the optimal WBG PSC and a narrow‐bandgap PSC bottom cell, the 4‐terminal all‐perovskite TSC achieves a remarkable 26.24% PCE. More importantly, this SAM based HTM exhibits impressive generality in bulk heterojunction OSCs rivalling PEDOT:PSS, with an impressive PCE of 18.84% obtained for PM6:BTP‐eC9 based devices. When scaling up the PM6:BTP‐eC9 device to 0.5 cm2 in area (0.71 cm × 0.71 cm), the SAM based OSCs afford a highest PCE of 16.33%. This work provides a perspective for the design of universal SAM based charge transport materials targeting PSCs and OSCs for facile large‐area fabrication.

Section: Resultsmentioning

confidence: 99%

Versatile Self‐Assembled Molecule Enables High‐Efficiency Wide‐Bandgap Perovskite Solar Cells and Organic Solar Cells

Liu

Advanced Energy Materials

et al. 2023

Advanced Energy Materials

“…The average carrier lifetime of SCSs‐perovskite films is shorter than that of the control film, indicating that the charge carriers are more easily extracted by the FTO conductive substrate. [ 33 ] The fast decay lifetime ( τ 1 ) associated with trap‐assisted non‐radiative recombination and the slow decay lifetime ( τ 2 ) attributed to the radiative recombination of free charge carriers in perovskite bulk. For FAPbBr 3 ‐perovskite film, the τ 1 of 57.8 ns was much longer than that of other ones, which manifests this film exhibits the lowest surface traps.…”

Section: Resultsmentioning

confidence: 99%

Single‐Crystal Seeds Inducing the Crystallization of High‐Performance α‐FAPbI₃ for Efficient Perovskite Solar Cells

Liu

et al. 2023

𝜶-phase formamidine lead iodine (𝜶-FAPbI 3 ) as a competitive candidate to pursue high-performance perovskite solar cells (PSCs) suffers from the weakness of random nucleation and disordered growth in chasing high-grade polycrystalline films. Here, single-crystal seeds crystallization (SCSC) method is proposed to obtain high-quality 𝜶-FAPbI 3 perovskite films for the first time. Six single-crystals seeds (CsPbBr 3 , CsPbI 3 , FAPbBr 3 , FAPbI 3 , MAPbBr 3 , and MAPbI 3 ) are employed to regulate 𝜶-FAPbI 3 perovskite crystallization. These seeds act as nucleation sites and allow the perovskite to grow directly. The rapid crystallization significantly improves the crystallinity of perovskite films with uniform morphology, large grain size, and less defects. Of particular note, FAPbBr 3 seed prefers to grow 𝜶-FAPbI 3 epitaxially from FAPbBr 3 @PbI 2 heterostructure through a halogen anion exchange process. The average grain size of FAPbBr 3-perovskite film is boosted to 2.6 μm, and the trap density reduced by 11 times. The resultant FAPbBr 3 -PSCs achieve a maximum power conversion efficiency (PCE) of 23.84% with a high open-circuit voltage of 1.18 V. The unencapsulated PSC retains 91% of the initial PCE after 3000 h of storage at ≈30-50% relative humidity and preserves 98.5% of the original value after 155 h illumination with maximum power point tracking.

“…[ 37 ] The perfect energy level matching between the NiO x HTL and perovskite layer is conductive to charge transport, resulting in less nonradiative recombination and less energy loss. [ 60 ] The steady‐state photoluminescence (PL) and time‐resolved PL (TRPL) characterizations were measured to directly examine the charge transfer dynamics at the HTL/PVK interfaces. As shown in Figure 3e, the PL intensity of the perovskite films on XBr/NiO x substrate is lower than that on bare NiO x substrate, indicating higher photoexcited carrier extraction efficiency.…”

Section: Resultsmentioning

confidence: 99%

Facile Modification on Buried Interface for Highly Efficient and Stable FASn_0.5Pb_0.5I₃ Perovskite Solar Cells with NiO_x Hole‐Transport layers^†

et al. 2023

Self Cite

Comprehensive SummaryFormamidinium (FA)‐based Sn‐Pb perovskite solar cells (FAPb0.5Sn0.5I3 PSCs) with ideal bandgap and impressive thermal stability have caught enormous attention recently. However, it still suffers from the challenge of realizing high efficiency due to the surface imperfections of the transport materials and the energy‐level mismatch between functional contacts. Herein, it is demonstrated that the modification on buried interface with alkali metal salts is a viable strategy to alleviate these issues. We systematically investigate the role of three alkali metal bromide salts (NaBr, KBr, CsBr) by burying them between the NiOx hole transport layer (HTL) and the perovskite light‐absorbing layer, which can effectively passivate interface defects, improve energy‐level matching and release the internal residual strain in perovskite layers. The device with CsBr buffer layer exhibits the best power conversion efficiency (PCE) approaching 20%, which is one of the highest efficiencies for FA‐based Sn‐Pb PSCs employing NiOx HTLs. Impressively, the long‐term storage stability of the unencapsulated device is also greatly boosted. Our work provides an efficient strategy to prepare desired FA‐based ideal‐bandgap Sn‐Pb PSCs which could be applied in tandem solar cells.This article is protected by copyright. All rights reserved.