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Morphology optimization of a photoactive layer has a crucial role in fabricating high-performance polymer solar cells (PSCs). If an active layer is cast from solution, then the unique properties of the donor and acceptor materials often lead to either excessive or insufficient phase separation, which adversely affect the performance of the device. Specifically, all-polymer solar cells (all-PSCs) introduce an added complexity in terms of morphology regulation due to the inherently flexible and entangled nature of polymer chains. In this work, we first introduced 3,5-dichloroanisole (DCA) as a solid additive, known for its good crystallinity and volatility, to refine the active-layer morphology in all-PSCs. Then, we combined 1-chloronaphthalene (CN) and DCA as dual additives, which effectively optimized the morphology of all-polymer blends. This combination favored charge transport and minimized charge recombination, leading to a higher fill factor across various systems. Notably, a device based on PM6:PY-DT processed with this dual-additives approach achieved an impressive power conversion efficiency (PCE) of 17.42%, outperforming the control device without any additive, which showed a PCE of 14.34%. Besides, dual additives were applied in other systems, revealing their universality. This work not only took advantages of both solvent and solid additives, but also effectively improved the performance of all-PSCs. [ABSTRACT FROM AUTHOR]

With the advancement of perovskite research, there is a growing urgency to address the imperative need for practical applications while simultaneously tackling the enduring challenges of material reliability and lead (Pb) toxicity. The crystallization, morphology and optical properties of the resultant film and device performance during solution processing are heavily influenced by the solution-based intermediate, a state determined using the coordination between solute and solvent. Solvent–solute coordination is closely correlated with solvent characteristics including ionization capabilities, dielectric constant, hydrolysis, and reactivity with solutes. Deionized water (D-water) characterized by its high polarity, ionization capability, and dielectric constant, when used as a co-solvent with dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), facilitates stronger coordination with CsI/SnI4 species in Cs2SnI6 precursor solution. This enhanced coordination leads to improved solvation, precursor reactivity, and solution homogeneity. Incorporating an appropriate amount of D-water as a co-solvent into Cs2SnI6 precursor solution allows for tuning solvent coordination and control over the resulting thin film crystallization and morphology. The co-solvent diluted optimized Cs2SnI6 thin film leads to the fabrication of energy-efficient broadband 4 × 3 photodetector arrays ranging from UV to NIR giving a responsivity of 5.5 A W−1 at a substantially lower bias voltage of −0.1 V with stable operation stability in ambient air. These findings underscore the potential advantages of solution-processed Cs2SnI6 perovskites in various optoelectronic applications. [ABSTRACT FROM AUTHOR]

The application of doctor-blading for flexible solar cells is considerably attractive due to its potential upscaling feasibility via a roll-to-roll process. Herein, we report the fabrication of efficient flexible Cu2ZnSn(S,Se)4 (CZTSSe) solar cells by doctor-blading under ambient conditions. The device efficiency is improved from 2.22% to 5.01% by Na incorporation, while the further enhancement is limited by inhomogeneous grain growth. To address this issue, we develop an alternative blading strategy via coating Na-containing and Na-free molecular inks by turns. By carefully tailoring this combination, compact and homogeneous CZTSSe films with large grains are obtained. Meanwhile, an appropriate amount of Na incorporation is found to be beneficial for grain growth, carrier transport, and defect passivation. Consequently, a flexible device with an efficiency of 9.63% based on the doctor-blading method is achieved. This work paves the way for the future upscaling of flexible CZTSSe solar cells via low-cost solution methods. [ABSTRACT FROM AUTHOR]

Flexible Cu2ZnSn(S,Se)4 (CZTSSe) solar cells have attracted considerable attention due to their potential application in specific areas such as power sources for wearable electronics. However, the over‐thick Mo(Sx,Se1−x)2 at the back contact is one of the factors that limit the device performance. Herein, a facile strategy to inhibit the thick Mo(Sx,Se1−x)2 layer by adding a proper proportion of sulfur during selenization is reported. It is found that the thickness of Mo(Sx,Se1−x)2 can be effectively tailored via tuning the proportion of S, enabling a substantial decrease in series resistance. The suppression mechanism is mainly ascribed to the change of orientation of Mo(Sx,Se1−x)2 induced by S, which limits the diffusion of Se to Mo. Accordingly, the total area efficiency of the flexible CZTSSe device improves significantly from 5.5 to 8.9% with the addition of 2% S, followed by a drop with more S. Furthermore, it is demonstrated that this strategy can also be applied to both kesterite and chalcogenide absorbers deposited on rigid Mo substrates to suppress the thick Mo(Sx,Se1−x)2 layer, indicating the universality of this method. Overall, this work provides a general, facile, and effective approach to modify the back contact interface without introducing extra blocking layers. [ABSTRACT FROM AUTHOR]

The use of transparent conducting oxides (TCO) as a back contact for Cu2ZnSn(S,Se)4 (CZTSSe) thin film solar cell enables light absorption from both front and rear sides and allows for the fabrication of semi‐transparent photovoltaic devices. However, the CZTSSe solar cell based on TCO substrate suffers from high parasitic losses owing to the long post‐annealing time at elevated temperature required for high‐quality absorber. This work aims to overcome this issue by carefully tailoring the annealing conditions to obtain high‐performance solar cell. Rapid thermal processing is used to instantaneously generate high Se vapor pressure at target temperature and shorten the annealing time. The crystalline quality, morphology, and particularly the photovoltaic performance of the resulting CZTSSe thin film are systematically investigated. It is found that the increase of annealing temperature and time improves the crystalline quality but unfortunately deteriorates the device performance owing to increasing parasitic losses. Increasing the amount of Se allows to get highly crystalline absorber within 7 min of annealing, yielding a total area 5.56% efficient CZTSSe solar cell with front illumination resulting from reducing parasitic losses. This work provides a simple approach to preserve the back contact without using a complex interfacial layer. [ABSTRACT FROM AUTHOR]

All‐inorganic perovskite of CsPbBr3 thin‐films solar cells has attracted increasing interest in recent years due to its potential long‐term stability over the generally used hybrid perovskites. Herein, all‐inorganic CsPbBr3 perovskites are doped with Eu2+ to enhance the efficiency of perovskite solar cells (PVSCs). The perovskite films exhibit a better crystallinity with smooth morphology after the introduction of rare‐earth elements. Hence, the hole‐transport layer‐free device with presence of Eu2+ and low‐cost carbon electrode achieves both enhanced efficiency and stability. In particular, the power conversion efficiency (PCE) enhances from 5.66% to 7.28% with high VOC of 1.45 V by optimizing the doping concentration of Eu2+. In addition, the storage stability measurements reveal excellent performances of PCE without encapsulation in air with relative humidity of 70–80%. These results can pave changes in future inorganic PVSCs. [ABSTRACT FROM AUTHOR]