Search

Organic‐inorganic lead halide perovskite are promising photovoltaic materials, but their intrinsic defects and crystalline quality severely deteriorate the solar cells efficiency and stability. Herein, potassium 1,1,2,2,3,3‐hexafluoroprop‐ane‐1,3‐disulfonimide (KHFDF) is introduced into PbI2 precursor solution to passivate various defects and improve the crystalline quality of perovskite films. It is found that KHFDF can inhibit PbI2 crystallization, thus tuning the crystal orientation and growth of perovskite films. Furthermore, KHFDF with dual‐functional sulfonyl group cannot only passivate grain boundaries (GBs), but also passivate the defects at GBs via strong interaction with undercoordinated Pb2+ and/or hydrogen bonding with FA+, while the K+ counter cations allow ionic interaction with undercoordinated I−. As a result, the KHFDF‐modified films exhibit high quality with a larger grain size and a reduced trap‐state density, thereby suppressing the trap‐state nonradiative recombination. And the devices show a champion efficiency up to 24.15%, benefiting from a sharp enhancement of open‐circuit voltage (Voc) of 1.183 V and fill factor of 81.78%. In addition, due to the enhanced humidity tolerance and chemical structure stability, the devices exhibit excellent long‐term humidity and thermal stability without encapsulation. [ABSTRACT FROM AUTHOR]

The outstanding optoelectronic properties of metal halide perovskites make them an attractive photovoltaic absorber material and has rapidly culminated in the development of highly efficient perovskite solar cells outperforming many conventional alternatives. However, the device stack still suffers from non‐negligible losses induced by various nonradiative recombination processes, which are not fully understood till date. This paper highlights recent findings attempting to understand the nature and origin of nonradiative recombination induced losses within the device stack, as well as the quantification of the magnitude and rates associated with key loss pathways mostly via steady state and transient contactless optical techniques. These studies show that nonradiative recombination processes occurring at interfaces are more dominant than those within the bulk of the perovskite absorber. However, recent findings also show that there remains room for improvement for the suppression of bulk nonradiative recombination. General routes for suppressing recombination processes within the bulk and at interfaces are discussed. Finally, current challenges are presented, which need to be overcome in order to obtain a deeper insight into the nature of defects at surfaces and within the bulk of perovskites, and ultimately enhance the power conversion efficiency of perovskite solar cells toward their thermodynamic efficiency limit. [ABSTRACT FROM AUTHOR]

Morphology optimization of active layer plays a critical role in improving the performance of organic solar cells (OSCs). In this work, a volatile solid additive‐assisted sequential deposition (SD) strategy is reported to regulate the molecular order and phase separation in solid state. The OSC adopts polymer donor D18‐Cl and acceptor N3 as active layer, as well as 1,4‐diiodobenzene (DIB) as volatile additive. Compared to the D18‐Cl:N3 (one‐time deposition of mixture) and D18‐Cl/N3 (SD) platforms, the D18‐Cl/N3(DIB) device based on DIB‐assisted SD method exhibits a finer phase separation with greatly enhanced molecular crystallinity. The optimal morphology delivers superior charge transport and extraction, offering a champion power conversion efficiency of 18.42% with significantly enhanced short‐circuit current density (Jsc) of 27.18 mA cm−2 and fill factor of 78.8%. This is one of the best performances in binary SD OSCs to date. Angle‐dependent grazing‐incidence wide‐angle X‐ray scattering technique effectively reveals the vertical phase separation and molecular crystallinity of the active layer. This work demonstrates the combination of volatile solid additive and sequential deposition is an effective method to develop high‐performance OSCs. [ABSTRACT FROM AUTHOR]

Interface engineering is widely applied in the one‐step antisolvent deposition for elevating efficiency of the perovskite solar cells (PSCs). Herein, an alcohol‐soluble small molecule, namely 2‐mercaptoimidazole (MI), is inserted between the hole transport layer and perovskite layer to form a cross‐linking bridge, which is built through: i) Coulomb interaction between the negatively charged MI and positively charged poly (3,4‐ethylene dioxythiophene); ii) electrostatic interaction between imidazolium cation and iodide anion in perovskite. The cross‐linking bridge can accelerate the hole transmission and inhibit interfacial recombination. Hence, by the optimum design of MI concentration, hysteresis‐free devices with a high power conversion efficiency of 20.68% are obtained. The overall efficiency increase is due to significantly enhanced short‐circuit current density from 21.28 to 23.45 mA cm−2 and slightly raised open‐circuit voltage from 1.06 to 1.08 V, suggesting that the MI modified layer can effectively improve the performance of the devices. Moreover, unencapsulated devices with MI interfacial modification show better environmental stability compared to the reference devices. This facile interfacial approach is promising for future commercialization of inverted PSCs. [ABSTRACT FROM AUTHOR]

A D-A copolymer donor D18 was developed, demonstrating an 18.22% PCE in single-junction organic solar cells. [ABSTRACT FROM AUTHOR]

A thiolactone-based D-A copolymer donor D16 was developed, demonstrating a 16.72% PCE in single-junction organic solar cells. [ABSTRACT FROM AUTHOR]

A polymer donor W1 with an ultra-wide bandgap of 2.16 eV demonstrates a 16.16% efficiency in organic solar cells. [ABSTRACT FROM AUTHOR]

Additive engineering is a simple and effective strategy to enhance the efficiency of organic solar cells (OSCs). However, traditional additives such as 1,8-diiodooctane (DIO) or 1-chloronaphthalene (CN), suffer from inferior stability, concentration sensitivity, and need additional thermal treatments, which are not desirable for industrial application. Here we introduce a simple, effective and versatile solid additive 1,3-diiodobenzene (1,3-DIB) into the OSCs. In comparison to the control devices, the 1,3-DIB treated OSCs exhibit significantly improved performance with a power conversion efficiency (PCE) of 16.90% for polymer OSCs and a PCE of 14.35% for binary all-small-molecule OSCs. Mechanism studies reveal that 1,3-DIB can improve charge transport and extraction, decrease charge recombination, enhance crystallinity and improve the phase separation. Furthermore, no thermal annealing is needed in PM6:Y6 based OSCs and the 1,3-DIB treated devices show excellent stability and reproducibility in both polymer and small molecule OSCs. Our results demonstrated that additive engineering is a powerful method to enhance the OSC performance. [Display omitted] • A simple and effective additive is developed for non-fullerene organic solar cells. • 16.9% efficiency organic solar cells are obtained with additive engineering. • Excellent device stability and processability are achieved with the additive. [ABSTRACT FROM AUTHOR]