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Organic small molecules have been proven to be the most efficient and predominantly employed hole transport layers (HTLs) in perovskite solar cells (PSCs), the reliance of HTLs on additives like Li‐TFSI has been unavoidable, particularly in terms of the well‐known Spiro‐OMeTAD. However, Li‐TFSI aggregation in HTL results in the decreased performance and stability of PSCs with serious hysteresis. It is an urgent need to explore a universal strategy to solve Li‐TFSI‐induced issues. Herein, a pyrene‐based organic semiconductor (PC) as an effective and universal additive for HTL application is developed. It is found that the introduction of PC can efficiently improve the hot carriers extraction/transfer and reduce the charge recombination in the device. Consequently, PSCs based on Spiro‐OMeTAD+PC as a HTL exhibit an excellent PCE of 24.80% with a negligible hysteresis, much higher than the control device (22.14%). Additionally, the efficiency of the PC incorporated into another well‐known X60 HTL‐treated device is enhanced to 24.12% from the control device (22.04%), confirming its universal application in PSCs. Moreover, PC can effectively suppress the Li+ aggregation in HTL, and the unencapsulated PSCs exhibit high stability. The findings in this work provide an effective and universal avenue to construct highly efficient and stable PSCs. [ABSTRACT FROM AUTHOR]

The mismatched energy level alignment at the hole transport interface is recognized to be a prominent limitation for the Cs2AgBiBr6‐based perovskite solar cell (PSC) to achieve high power conversion efficiency (PCE) but has not been well investigated yet. In order to solve this problem to some extent, it is proposed to balance the energy offset at the Cs2AgBiBr6 and hole transport material (HTM) interface to reduce the hole transport barriers, and a novel HTM TPTI‐TPA2F with deep level is designed to implement this strategy. The research demonstrates that, on the one hand, the planar π‐conjugation and the presence of multiple heteroatoms on TPTI‐TPA2F facilitate the formation of well‐oriented film and surface defect passivation; on the other hand, the higher film ionization potential of TPTI‐TPA2F effectively balances the energy barrier for hole transport. As a result, improved hole‐selective contact is achieved with TPTI‐TPA2F as HTM, and the interfacial energy loss is suppressed. Correspondingly, the optimized Cs2AgBiBr6 PSCs using the TPTI‐TPA2F HTM without doped feature an excellent PCE of 4.05% and a high open circuit voltage of 1.15 V, with much improved long‐term humidity and thermal stability. This work provides an attractive strategy for developing efficient Cs2AgBiBr6 PSCs. [ABSTRACT FROM AUTHOR]

Modulating perovskite crystallization and understanding hot carriers (HCs) dynamics in perovskite films are very critical to achieving high‐performance perovskite solar cells (PSCs). Herein, a small organic molecule (6BAS) with multisite anchors (C═O) as an efficient additive is introduced into PbI2 precursors to modulate perovskite crystallization during two‐step sequential deposition. The chemical interaction between 6BAS and PbI2 enables more preferential PbI2 crystal with enlarged interplanar spacing of PbI2 lattice, which is beneficial to the penetration of organic ammonium salts into PbI2 layer and the complete conversion to perovskite, consequently promoting the preferential crystallization of perovskite to realize high‐quality perovskite films with larger grain size and reduced defect state. By ultrafast spectroscopy, it is found that the incorporation of 6BAS can efficiently prolong HCs cooling, which helps to enhance HCs transfer and retard the charge carrier recombination in device. As a result, 6BAS doped‐PSCs efficiency significantly enhances to 25.32% from 22.91%. The target device achieves the enhanced long‐term stability. Only a 6% efficiency degradation is realized for un‐encapsulated device with 6BAS after 70 days under N2. Meanwhile, the 6BAS‐treated device retains 95% of its initial PCE after 1160 h of operation at the maximum power point under continuous AM 1.5 G illumination. [ABSTRACT FROM AUTHOR]

To elevate the performance and durability of perovskite solar cells, a holistic approach to mitigating defects throughout the device is essential. While advancements in refining top interfaces have been significant, the potential of stabilizing buried interfaces and grain boundaries has not been fully tapped. The research underscores the transformative impact of guanidine phosphate (GP), a chemical agent that converts surplus PbI2 into a low‐dimensional perovskite, thus reinforcing the stability of both buried interfaces and grain boundaries. Employing GP on quantum dot tin dioxide (QD‐SnO2) surfaces revealed an exceptional grain wrapping effect at these critical junctures, as revealed by high‐resolution transmission electron microscopy. This novel low‐dimensional perovskite enveloping strategy not only passivates the grain boundaries but also delays the cooling of hot carriers, thereby diminishing charge carrier recombination. This strategy exhibits an enhanced power conversion efficiency, rising from 23.16% to 24.55%. Moreover, the modified device sustains over 90% of their initial efficiency after 1000 h of maximum power point tracking under one sun illumination and maintain 90% efficiency after 1400 h in moderate humidity, all achieved without the encapsulation. This breakthrough points to a robust method for augmenting perovskite solar cell, promising a more durable, and efficient solar energy. [ABSTRACT FROM AUTHOR]

2D Dion–Jacobson (DJ) tin halide perovskite shows impressive stability by introducing diamine organic spacer. However, due to the dielectric confinement and uncontrollable crystallization process, 2D DJ perovskite usually exhibits large exciton binding energy and poor film quality, resulting in unfavorable charge dissociation, carrier transport and device performance. Here, the ortho‐, meta‐, and para‐isomers of phenylenediamine (PDA) are designed for 2D DJ tin halide perovskites. Theoretical simulation and experimental characterizations demonstrate that compared with p‐PDA and m‐PDA, o‐PDA shows larger dipole moment, which further reduces the exciton binding energy for the 2D perovskites. Besides, there is a strong hydrogen bond interaction between o‐PDA cation and inorganic octahedron, which not only improves the structural stability, but also induces larger aggregates in the precursor to form dense and uniform high‐quality films, and strengthens the antioxidant barrier. More interestingly, femtosecond transient absorption further proves that o‐PDA organic spacers can reduce unfavorable small n‐phases, resulting in sufficient and effective charge transfer between different n‐value. As a result, the 2D DJ (o‐PDA)FA3Sn4I13 solar cells achieve a record power conversion efficiency of 7.18%. The study furnishes an effective method to optimize the carrier transport and device performance by tailoring the chemical structure of organic spacers. [ABSTRACT FROM AUTHOR]

Slowing hot carrier (HC) cooling in lead halide perovskites is important to further improve the efficiency of perovskite solar cells (PSCs). Herein, we found that HC cooling can be efficiently prolonged by incorporating an organic small molecule (TDGA) into the perovskite film as an additive through transient absorption spectroscopy measurements, which is conducive to the extraction of the HC energies by the carrier transport layers and reduces charge carrier recombination, consequently improving the efficiency of the TDGA-doped device. [ABSTRACT FROM AUTHOR]

Understanding the effect of additive on the interfacial charge‐carrier transfer dynamics is very crucial to obtaining highly efficient perovskite solar cells (PSCs). Herein, we designed a simple additive, dimethyl oxalate (DO), functioning as an effective defect passivator of perovskite grain boundaries via the coordination interaction between the carbonyl (C=O) and the exposed Pb2+. The modification with DO produces pinhole‐free and compact perovskite films, enhancing the transportation capability of carriers. As a consequence, the DO‐treated PSCs exhibited a power conversion efficiency (PCE) of 22.19%, which is significantly higher than that of the control device without additive (19.58%). More importantly, detailed transient absorption characterization reveals that the use of additive can decrease the hot‐carrier cooling dynamics, improve the carrier transfer, and eliminate nonradiative recombination in PSCs. This present work provides a profound understanding the additives effect on the carrier dynamics in PSCs toward the Shockley−Queisser limit. [ABSTRACT FROM AUTHOR]

Lithium bis(trifluoromethanesulfonyl)imide (Li‐TFSI) has been identified as the most used and effective p‐dopant for hole transport layer (HTL) in perovskite solar cells (PSCs). However, the migration and agglomeration of Li‐TFSI in HTL negatively impact PSCs performance and stability. Herein, we report an effective strategy for adding a liquid crystal organic small molecule (LQ) into Li‐TFSI doped (2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐ spirobifluorene (Spiro‐OMeTAD) HTL. It was found that the introduction of LQ into Spiro‐OMeTAD HTL can efficiently enhance the charge carrier extraction and transportation in device, which can strongly retard the charge carrier recombination in device. Consequently, the PSCs efficiency is significantly enhanced to 24.42 % (Spiro‐OMeTAD+LQ) from 21.03 % (Spiro‐OMeTAD). The chemical coordination between LQ and Li‐TFSI can strongly confine Li+ ions migration and agglomeration of Li‐TFSI, thus, achieving the enhanced device stability. Only a 9 % efficiency degradation is observed for un‐encapsulated device prepared with Spiro‐OMeTAD and LQ after 1700 h under air environment, while the efficiency drops by 30 % for the reference device. This work provides an effective strategy for improving the efficiency and stability of PSCs, and gives some important insights for understanding intrinsic hot carriers dynamics for perovskite‐based optoelectronic devices. [ABSTRACT FROM AUTHOR]

Surface passivation engineering of perovskite films via organic functional small molecules has emerged as an effective strategy for improving the efficiency and stability of perovskite solar cells (PSCs). However, a systematic understanding of underlying mechanisms behind these improvements is still missing. In this work, two new naphthalimide‐based organic small molecules (PX, X = F, I) are designed and employed to efficiently passivate the surface defects of perovskite films in PSCs. Consequently, superior photovoltaic properties for PI‐treated PSCs are achieved with a power conversion efficiency of 23.06%, which is significantly higher than that of the reference device without passivators (20.45%). Theoretical calculations reveal that PX can give rise to interfacial electrical dipole. It is found that incorporating a dipole interlayer between perovskite layer and hole transport layer can enhance ultrafast charge‐carrier injection and suppress the charge‐carrier recombination in device, which is illustrated by transient absorption spectroscopy. These present results can provide valuable information on the understanding interfacial charge‐carrier dynamics in PSCs to further improve the device performance. [ABSTRACT FROM AUTHOR]

A profitable approach for improving the stability of n‐i‐p planar perovskite solar cell (PSC) is developing dopant‐free hole transport materials (HTMs) with desirable intrinsic charge transport properties. In this work, by adopting a metal‐free catalytic intramolecular C─C coupling reaction, a carbazole dimer‐based fused‐ring is synthesized, and further developed a small molecular dopant‐free HTM abbreviated as NCz‐DM with appropriate energy level, excellent hole transport and film formation properties. Applied in n‐i‐p planar PSC, an impressive power conversion efficiency (PCE) of 24.0% is achieved, together with enhanced humidity, thermal and light stability, which is among the high level of ever‐reported results for PSCs utilizing small molecular dopant‐free HTM. [ABSTRACT FROM AUTHOR]

A novel conjugated self-assembled molecule, XS13 , is tailor-made for application in wide-bandgap (∼1.8 eV) inverted perovskite solar cells (PSCs). XS13 could facilitate hole transfer at perovskite/hole transporting material interface, thereby effectively suppressing photo-induced halide segregation. As a result, PSCs incorporating XS13 demonstrate a champion efficiency of 19.20%, coupled with outstanding stability under both light and electrical conditions. [Display omitted] • Proposing a novel approach to regulate the interface carrier dynamics of WBG PSCs through the rational chemistry design of a conjugated SAM-based hole-transporting molecule, XS13. • Demonstrating that XS13 facilitates rapid hole extraction and transfer, suppressing charge accumulations and electron recombination at the perovskite/HTM interface and significantly mitigating halide ions migration under light or electricity stress. • Achieving outstanding PCE of up to 19.20 % in XS13 -based WBG PSCs, surpassing control devices (2PACz; 16.41 %), making it one of the highest efficiencies in WBG (∼1.8 eV) PSCs. • Introducing a compelling and innovative strategy for the rational design of hole-transporting molecules, emphasizing the importance of controlled properties in advancing the efficiency and stability of PSCs. Charge accumulations and electron recombination at the interfaces between perovskites and charge transporting materials are two critical factors significantly hindering the power conversion efficiency (PCE) and device stability of wide-bandgap perovskite solar cells (WBG PSCs). Herein, we tailor-made a self-assembled molecule (SAM), termed XS13 , featuring an enlarged π-donor and a π-linker, to regulate the interface carrier dynamics in ∼1.8 eV WBG PSCs. Ultrafast spectroscopy clearly demonstrated that the XS13 facilitated the rapid extraction and transfer of photo-generated holes compared to the reference SAM-2PACz. Consequently, WBG PSCs based on XS13 achieved an outstanding PCE of up to 19.20 %, surpassing that of control devices (16.41 %). Furthermore, XS13 -based WBG PSCs exhibited a remarkable suppression of light/electricity-induced halide ions migration, leading to significantly improved device stability. Our findings offer a new strategy for the rational design of hole transporting molecules with controlled properties to enhance device performance of PSCs. [ABSTRACT FROM AUTHOR]

A novel multi-functional interface material (TAAPyr) is first developed as a defect passivation layer and a protect layer against moisture for PSCs application. Consequently, the efficiency of TAAPyr-based device can increase form 20.37% to 22.45%, with an unencapsulated device retaining 90% of its initial efficiency after storage for 600h at ∼65% humidity. [Display omitted] • A hydrophobic multi-functional interface material is developed for PSCs application. • TAAPyr-treated PSCs shows an improvement in efficiency from 20.37% to 22.45%. • Device long-term stability has greatly been enhanced. Surface treatment of perovskite films with interface materials is an effective strategy to resolve trap-mediated nonradiative recombination toward high efficiency and stability of perovskite solar cells (PSCs). However, interface materials for multi-functional treatment have been rarely investigated in PSCs. In this work, a novel pyrene-based organic material (TAAPyr) is first introduced as a defect passivation layer and a protect layer against moisture for PSCs application. With the TAAPyr interfacial modification, both perovskite surface defects and nonradiative recombination are effectively decreased as well as the carrier transport in device is also enhanced, As a consequence, the best power conversion efficiencies (PCE) up to 22.45% for TAAPyr-based device was obtained, clearly outperforming the control one (20.37%). Moreover, it was found that the π-conjugated TAAPyr can promote intermolecular face-to-face stacking on the surface perovskite film, which is favorable to making the perovskite surface more hydrophobic and consequently enhance PSCs long-term stability. The un-encapsulated PSCs can retain 92% of the initial PCE after storage for 600 h at ∼65% RH, in comparison with 64% efficiency retention of the device without TAAPyr under the same conditions. This work presents a new strategy to enhance the efficiency and stability of PSCs by multi-functional π–conjugated passivator. [ABSTRACT FROM AUTHOR]

In this study, a two-step method was used to prepare CsPbBr 3 perovskite thin films. The first step is to spin-coat PbBr 2 solution on the ITO substrate, and the second step is to soak CsBr solution with different soaking times. The structure of the proposed films is gradually changing from CsPb 2 Br 5 to CsPbBr 3 as the soaking times increase. The self-powered UV photodetector with P-I-N structure is fabricated with structure configuration of ITO substrate/ZnO seed layer/ZnO nanorod/CsPbBr 3 /CuSCN/Ag. Diethyl sulfide (DES) is used as solvent for preparing CuSCN solution, and different DES removal methods on the device's performance is investigated. In terms of device performance, the response time is less than 10 ms; the responsivity is partially increased from 410 mA/W to 530 mA/W, and the lowest dark current reaches 1.28 × 10−12 A which increases the on/off ratio to 4.2 × 106. The proposed devices show high on/off under zero-bias condition, as compared to the reported data. [Display omitted] • The device had the highest responsivity up to 481.2 mA/W, and the highest On/Off ratio is 8 × 104 when the number of immersion was 3. • When CuSCN was treated with LPT for 60 min, there is the lowest dark current up to 1.28 × 10−12 A, and the highest On/Off ratio is 4.26 × 106. • We fabricated a PIN self-powered perovskite photosensors device with large crystal size and the best film quality. [ABSTRACT FROM AUTHOR]

Carbazole derivatives are widely used as electron donors for the construction of hole transport materials (HTMs) for perovskite solar cells (PSCs), whose performance depends strongly on the structure and properties of the π-bridges. In this paper, we report a new HTM, ACR-Cz-DM, using 9,10-dihydroacridine (ACR) as a π-bridge and N 3 ,N 6 -bis(9,9-dimethyl-9H-fluoren-2-yl)- N 3 ,N 6 -bis(4-methoxyphenyl)-9 H -carbazole-3,6-diamine (Cz-DM) as a peripheral electron donor. Cz-DM well satisfies the need of the ACR core for a peripheral donor with weak electron donation and high conjugation capacity. Owing to the excellent hole mobility and conductivity, good film formation and outstanding charge extraction and transport ability of ACR-Cz-DM, the photoelectric conversion efficiency (PCE) of FAPbI 3 -based PSCs using ACR-Cz-DM as HTM attained 21.37%, which is better than that of Spiro-OMeTAD-based PSCs (20.10%) under the same conditions. This work provides a promising demonstration of the design principles of ACR-based HTMs. • A novel acridine bridging hole transport material (HTM) ACR-Cz-DM is reported. • ACR-Cz-DM exhibits excellent charge transfer capability and suitable energy level. • The FAPbI 3 -device using ACR-Cz-DM as HTM achieves a PCE of 21.37%. [ABSTRACT FROM AUTHOR]

• A new bottom surface modification strategy is demonstrated by introducing zwitterionic polysquaraine into PTAA. • PASQ-IDT ameliorated the wettability of PTAA film and improved the perovskite film quality. • Promoted carrier extraction at the perovskite/HTL interface and reduced trap density were realized by modified HTL. • MAPbI 3-x Cl x -based inverted PSCs with the modified PTAA HTL showed efficiency exceeding 21 %. In inverted perovskite solar cells (PSCs), perovskite crystals grow on the bottom hole transporting layer (HTL), and the HTL not only functions to extract and transport holes, but also manipulates the perovskite crystallization process and affects perovskite film quality. Poly(triarylamine) (PTAA) represents one of the most widely used and highly-efficient hole transport material in inverted PSCs. However, strong hydrophobicity makes the PTAA layer incompatible to the polar perovskite precursor solution, consequently, solvent pre-wetting or introducing an amphiphilic interlayer is always applied to PTAA layer before depositing perovskite film. Herein, we develop an efficient approach of modifying the bottom interface of perovskite layer by blending PTAA with a p-type zwitterionic polysquaraine (PASQ-IDT). The zwitterionic PASQ-IDT not only significantly improves the wettability of PTAA film toward perovskite precursor, leading to large perovskite grains with uniform sizes, but also enables more efficient carrier extraction at the perovskite/HTL interface, accompanied with efficiently reduced trap densities at the bottom surface. As a result, MAPbI 3-x Cl x -based inverted PSCs utilizing the modified PTAA HTL show an impressive efficiency exceeding 21 %, which represents a high value for MA-based inverted PSCs. [ABSTRACT FROM AUTHOR]