Dimensional Regulation of Organic n-Type Dopants for Highly Efficient Perovskite Solar Cells and Modules.

A strong n-type perovskite layer is crucial in achieving high open-circuit voltage (V) and power conversion efficiency (PCE) in the p-i-n solar cells, as the weak n-type perovskites result in a loss of V, and the p-type perovskites contain numerous electron traps that cause the severe carrier recombination. Here, three types of perylene diimide (PDI) based small molecule dopants with different dimensions, including 1D-PDI, 2D-PDI, and 3D-PDI are designed, to produce heavier n-type perovskites. The PDI-based molecules with Selenium atoms have a strong electron-donating ability, effectively enlarging the quasi-Fermi level splitting within the perovskites.

Dual-Asymmetric Solid Additive Enables Eco-friendly All-Polymer Solar Cells with Over 19 % Efficiency and Excellent Stability.

The optimization of morphology in all-polymer solar cells (all-PSCs) often relies on the use of solvent additives. However, their tendency to remain trapped in the device due to high boiling points leads to performance degradation over time. In this study, we introduce a novel approach involving the design and synthesis of one dual-asymmetric solid additive featuring mono-brominated-asymmetric dithienothiophene (SL-1).

Phenanthroline-Based Low-Cost and Efficient Small-Molecule Cathode Interfacial Layer Enables High-Performance Inverted Perovskite Solar Cells via Doctor-Blade Coating.

Perovskite solar cells (PSCs) have recently emerged as highly efficient and cutting-edge photovoltaic technology. In inverted PSCs, challenges are focused on the insufficient interface contact and energy level misalignment between the electron transport layer (ETL) and the metal electrode. Hence, the cathode interfacial layer (CIL) plays a crucial role in regulating energy levels and enabling charge extraction in PSCs.

Enhanced Performance and Stability of Perovskite Solar Cells Through Surface Modification with Benzocaine Hydrochloride.

Current development of inverted p-i-n perovskite solar cells (PSCs), with nickel oxide as the hole transport layer, is progressing toward lower net costs, higher efficiencies, and superior stabilities. Unfortunately, the high density of defect-based traps on the surface of perovskite films significantly limits the photoelectric conversion efficiency and operational stability of perovskite solar cells. Finding cost-effective interface modifiers is crucial for the further commercial development of p-i-n PSCs.

Two-Second-Annealed 2D/3D Perovskite Films with Graded Energy Funnels and Toughened Heterointerfaces for Efficient and Durable Solar Cells.

The 2D/3D perovskite heterostructures have been widely investigated to enhance the efficiency and stability of perovskite solar cells (PSCs). However, rational manipulation of phase distribution and energy level alignment in such 2D/3D perovskite hybrids are still of great challenge. Herein, we successfully achieved spontaneous phase alignment of 2D/3D perovskite heterostructures by concurrently introducing both 2D perovskite component and organic halide additive.

Additive-Stabilized Emission Centers for Blue Perovskite Light-Emitting Diodes.

The performance of the blue perovskite light-emitting diodes (PeLEDs) is limited by the low photoluminescence quantum yields (PLQYs) and the unstable emission centers. In this work, we incorporate sodium bromide and acesulfame potassium into a quasi-2D perovskite to control the dimension distribution and promote the PLQYs. Benefiting from the efficient energy cascade channel and passivation, the sky-blue PeLED has an external quantum efficiency of 9.

Phosphotungstate-Based Anode Interfacial Material for Constructing High-Performance Polymer Solar Cells with a Fill Factor over 80.

In the field of organic solar cells (OSCs), the interfacial layer plays the role of enhancing carrier extraction/transportation, inhibiting their recombination, etc. In contrast to the wide variety of cathode interfacial materials with good modification ability, much less effort has been reported for anode interfacial materials. In this study, we report a polyoxometalate-based inorganic molecular cluster, zinc phosphotungstate (ZnPWO, denoted ZnPW), as an anode interfacial layer.

Secondary Anti-Solvent Treatment for Efficient 2D Dion-Jacobson Perovskite Solar Cells.

Surface defects-mediated nonradiative recombination plays a critical role in the performance and stability of perovskite solar cells (PSCs) and surface post-treatment is widely used for efficient PSCs. However, the commonly used surface passivation strategies are one-off and the passivation defect ability is limited, which can only solve part of the defects in the topmost surface area. Here, a secondary anti-solvent strategy is proposed to further reduce surface defects based on conventional surface passivation for the first time.

Dopant-Free Bithiophene-Imide-Based Polymeric Hole-Transporting Materials for Efficient and Stable Perovskite Solar Cells.

The development of hole-transport materials (HTMs) with high mobility, long-term stability, and comprehensive passivation is significant for simultaneously improving the efficiency and stability of perovskite solar cells (PVSCs). Herein, two donor-acceptor (D-A) conjugated polymers PBTI and PFBTI with alternating benzodithiophene (BDT) and bithiophene imide (BTI) units are successfully developed with desirable hole mobilities due to the good planarity and extended conjugation of molecular backbone. Both copolymers can be employed as HTMs with suitable energy levels and efficient defect passivation.

High-Performance Deep Red Colloidal Quantum Well Light-Emitting Diodes Enabled by the Understanding of Charge Dynamics.

Colloidal quantum wells (CQWs) have emerged as a promising family of two-dimensional (2D) optoelectronic materials with outstanding properties, including ultranarrow luminescence emission, nearly unity quantum yield, and large extinction coefficient. However, the performance of CQWs-based light-emitting diodes (CQW-LEDs) is far from satisfactory, particularly for deep red emissions (≥660 nm). Herein, high efficiency, ultra-low-efficiency roll-off, high luminance, and extremely saturated deep red CQW-LEDs are reported.

Doping Compensation Enables High-Detectivity Infrared Organic Photodiodes for Image Sensing.

Infrared organic photodiodes have gained increasing attention due to their great application potentials in night vision, optical communication, and all-weather imaging. However, the commonly occurring high dark current and low detectivity impede infrared photodetectors from portable applications at room temperature. Herein, an efficient and generic doping compensation strategy is developed to improve the detectivity of infrared organic photodiodes.

Architecturing 1D-2D-3D Multidimensional Coupled CsPbI Br Perovskites toward Highly Effective and Stable Solar Cells.

Despite the rapid development of CsPbI Br (0 ≤ x ≤ 3) inorganic perovskite solar cells, associated with their superior thermal stability, their low moisture stability limits their commercial deployment. In this study, 1D-2D-3D multidimensional coupled perovskites are prepared by means of an in situ self-integration approach. This pioneering method allows incorporating thus far unreported 1D-Tpy Pb I and 2D-TpyPb I (Tpy; terpyridine) perovskites.

Molecularly Engineered Interfaces in Metal Halide Perovskite Solar Cells.

Perovskite solar cells (PSCs) have emerged as a promising candidate for next-generation thin-film photovoltaic technology owing to their excellent optoelectronic properties and cost-effectiveness. To gain the full potential of device performance, an in-depth understanding of the surface/interface science is an urgent need. Here, we present a review of molecularly engineered studies on interface modifications of PSCs.

Graded 2D/3D Perovskite Heterostructure for Efficient and Operationally Stable MA-Free Perovskite Solar Cells.

Almost all highly efficient perovskite solar cells (PVSCs) with power conversion efficiencies (PCEs) of greater than 22% currently contain the thermally unstable methylammonium (MA) molecule. MA-free perovskites are an intrinsically more stable optoelectronic material for use in solar cells but compromise the performance of PVSCs with relatively large energy loss. Here, the open-circuit voltage (V ) deficit is circumvented by the incorporation of β-guanidinopropionic acid (β-GUA) molecules into an MA-free bulk perovskite, which facilitates the formation of quasi-2D structure with face-on orientation.

Dopant-Free Organic Hole-Transporting Material for Efficient and Stable Inverted All-Inorganic and Hybrid Perovskite Solar Cells.

Designing new hole-transporting materials (HTMs) with desired chemical, electrical, and electronic properties is critical to realize efficient and stable inverted perovskite solar cells (PVSCs) with a p-i-n structure. Herein, the synthesis of a novel 3D small molecule named TPE-S and its application as an HTM in PVSCs are shown. The all-inorganic inverted PVSCs made using TPE-S, processed without any dopant or post-treatment, are highly efficient and stable.

Highly efficient all-inorganic perovskite solar cells with suppressed non-radiative recombination by a Lewis base.

All-inorganic perovskite solar cells (PVSCs) have drawn increasing attention because of their outstanding thermal stability. However, their performance is still inferior than the typical organic-inorganic counterparts, especially for the devices with p-i-n configuration. Herein, we successfully employ a Lewis base small molecule to passivate the inorganic perovskite film, and its derived PVSCs achieved a champion efficiency of 16.

Dopant-Free Squaraine-Based Polymeric Hole-Transporting Materials with Comprehensive Passivation Effects for Efficient All-Inorganic Perovskite Solar Cells.

Development of high-performance dopant-free hole-transporting materials (HTMs) with comprehensive passivation effects is highly desirable for all-inorganic perovskite solar cells (PVSCs). Squaraines (SQs) could be a candidate for dopant-free HTMs as they are natural passivators for perovskites. One major limitation of SQs is their relatively low hole mobility.

Dual Interfacial Design for Efficient CsPbI Br Perovskite Solar Cells with Improved Photostability.

A synergic interface design is demonstrated for photostable inorganic mixed-halide perovskite solar cells (PVSCs) by applying an amino-functionalized polymer (PN4N) as cathode interlayer and a dopant-free hole-transporting polymer poly[5,5'-bis(2-butyloctyl)-(2,2'-bithiophene)-4,4'-dicarboxylate-alt-5,5'-2,2'-bithiophene] (PDCBT) as anode interlayer. First, the interfacial dipole formed at the cathode interface reduces the workfunction of SnO , while PDCBT with deeper-lying highest occupied molecular orbital (HOMO) level provides a better energy-level matching at the anode, leading to a significant enhancement in open-circuit voltage (V ) of the PVSCs. Second, the PN4N layer can also tune the surface wetting property to promote the growth of high-quality all-inorganic perovskite films with larger grain size and higher crystallinity.

Modulation of recombination zone position for quasi-two-dimensional blue perovskite light-emitting diodes with efficiency exceeding 5.

In recent years, substantial progress has been made in developing perovskite light-emitting diodes with near-infrared, red and green emissions and over 20% external quantum efficiency. However, the development of perovskite light-emitting diodes with blue emission remains a great challenge, which retards further development of full-color displays and white-light illumination based on perovskite emissive materials. Here, firstly, through composition and dimensional engineering, we prepare quasi-two-dimensional perovskite thin films with improved blue emission, taking advantages of reduced trap density and enhanced photoluminescence quantum yield.

Fluoro- and Amino-Functionalized Conjugated Polymers as Electron Transport Materials for Perovskite Solar Cells with Improved Efficiency and Stability.

We report here novel bifunctionalized electron transport materials (ETMs) that can improve the efficiency and stability of perovskite solar cells (PVSCs) simultaneously. By functionalizing n-type conjugated polymers with fluoro and amino side chains, PN, PN-F25%, and PN-F50% with varied contents of fluoro and amino side chains are prepared. It is found that the amino side chains in ETMs efficiently improve the interface contact and electron collection of PVSCs, with improved power conversion efficiency from 14.

Enhancing the Performance of Inverted Perovskite Solar Cells via Grain Boundary Passivation with Carbon Quantum Dots.

Nonradiative recombination, the main energy loss channel for open circuit voltage ( V), is one of the crucial problems for achieving high power conversion efficiency (PCE) in inverted perovskite solar cells (PSCs). Usually, grain boundary passivation is considered as an effective way to reduce nonradiative recombination because the defects (uncoordinated ions) on grain boundaries are passivated. We added the hydroxyl and carbonyl functional groups containing carbon quantum dots (CQDs) into a perovskite precursor solution to passivate the uncoordinated lead ions on grain boundaries.