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Despite tremendous progress in the power conversion efficiency (PCE) of perovskite solar cells (PeSCs), the long-term stability issue remains a significant challenge for commercialization. In this study, by blending organic halide salts, phenylethylammonium halide (PEAX, X = I, Br), with CH3NH3PbI3 (MAPbI3), we achieved remarkable enhancements in the water-repellency of perovskite films and long-term stability of PeSCs, together with enhanced PCE. The hydrophobic aromatic PEA+ group in PEAX protects the perovskite film from destruction by water. In addition, the smaller halide Br- in PEABr restructures MAPbI3 to form MAPbI3-xBrx during post-annealing, leading to lattice contraction with beneficial crystallization quality. The perovskite films modified by PEAX exhibited excellent water resistance. When the perovskite films were directly immersed in water, no obvious decompositions were observed, even after 60 s. The PEAX-decorated PeSCs exhibited considerable long-term stability. Under high-humidity conditions (60 ± 5%), the PEAX-decorated PeSCs held 80.5% for PEAI and 85.2% for PEABr of their original PCE after exposure for 100 h, whereas the pristine PeSC device lost more than 99% of its initial PCE after exposure for 60 h under the same conditions. Moreover, compared to the pristine device with a PCE of 13.28%, the PEAX-decorated PeSCs exhibited enhanced PCEs of 17.33% for the PEAI device and 17.18% for the PEABr device.

A new type of polymer matrix electrolyte based on modified polybutadiene (modified PB) was developed for dye-sensitized solar cells (DSSCs) to improve their stability. The modified PB was fabricated by cross-linking the reaction of polybutadiene with siloxane groups as a substitute sol-gel process. A DSSC device using the modified PB matrix electrolyte showed an open-circuit voltage of 0.64 V, a short-circuit current density of 15.00 mA/cm2, and a fill factor of 0.58 under photointensity of 100 mW/cm2 at AM 1.5, consequently leading to an overall solar energy conversion efficiency of 5.49%. The DSSC device using the modified PB matrix electrolyte improved the conductivity, and the charge transfer ability showed the outstanding stability of the device.

Perovskite solar cells (PeSCs) attract significant attention owing to their numerous advantages such as superior optical/electrical properties and solution processability. However, the existence of defects in the grain boundaries still prevents high performance and stable PeSCs. Here, we present a simple yet effective momentary spinning (MS) method for passivating defect sites in the grain boundaries of PeSCs. By applying the MS method to the perovskite active layer, we achieve infiltration of p-type hole transporting materials (HTMs) with selective hole transport into grain boundaries, thereby reducing leakage current, suppressing nonradiative recombination loss, and achieving efficient hole extraction. The MS-fabricated PeSCs remarkably enhance device performance, displaying higher short-circuit current (Jsc), open-circuit voltage (Voc), and fill factor (FF) than the conventional spin-coating (SC) devices. The best device exhibits a Jsc of 23.2 mA cm−2, a Voc of 0.99 V, and an FF of 0.81, yielding a power conversion efficiency (PCE) of 18.6%. In addition, passivating hydrophilic grain boundaries with hydrophobic HTM improves the moisture stability of the device. When device performance is monitored for over 20 days of storage, the MS device exhibits improved stability with over 80% of the initial PCE compared to the SC device with only 50%.

In this study, we investigate the effects of polymer backbone curvature on the performance of non-fullerene organic solar cells (NFA-OSCs) fabricated using an electron-donating π-conjugated polymer and a non-fullerene electron-acceptor (NFA), 3,9-bis[2-methylene(3-(1,1-dicyanomethylene)-indanone)]-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2ʹ,3ʹ-dʹ]-s-indaceno[1,2-b:5,6-bʹ]dithiophene (ITIC). The NFA-OSCs are fabricated using structurally similar bis(pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione) (BPPD)-based π–conjugated polymers, i.e., P1 and P2, and they indicate almost identical absorption and energy levels but dissimilar backbone curvatures. P1 comprises two-dimensional conjugated benzodithiophene (BDTT) and thiophene π-bridged BPPD derivatives, and P2 comprises BDTT and thieno[3,2-b]thiophene π-bridged BPPD derivatives. The absorption maximum and highest occupied/lowest unoccupied molecular orbital levels of P1 and P2 are ~505 nm and ~˗5.4/˗3.4 eV, respectively. However, P1 shows a twisted backbone, whereas P2 exhibits a well-controlled wavy backbone owing to the presence of slightly different-structured π-bridges, such as thiophene and thieno[3,2-b]thiophene, on their backbones. The NFA-OSCs are fabricated with the structures of glass-ITO/PEDOT:PSS/P1 and P2:ITIC+0.5 vol% 1,8-diiodoctane (DIO)/PFN-Br/Al provide quite different device performances with power conversion efficiency of 0.88% and 6.25%, respectively. In general, the curvature of the polymer backbone significantly affects the nanoscale network formation between the polymer and ITIC, thereby resulting in a significant difference in the carrier transport and photovoltaic performances of the NFA-OSCs.

A new approach is presented here to maximize the efficiency of ternary blend polymer solar cells (ter-PSCs). The properties of co-absorbing wide band-gap polymers are fine-tuned via the insertion of two different appropriate electron-acceptor units on their backbone in different ratios, and the resulting polymers are utilized as a co-absorbent on ter-PSCs. The copolymerization of benzodithiophene, pyrrolopyrrole-1,3-dione, and difluoro-benzothiadiazole derivatives at three different ratios, 1.00:1.00:0.00, 1.00:0.50:0.50, and 1.00:0.25:0.75, produces the polymers P1–P3. The absorption bands of P1–P3 are gradually red-shifted, and the band-gaps are reduced. The crystallinity of the polymers is increased in the order of P1