lizhendong

Organic solar cells (OSCs) made of donor/acceptor bulk-heterojunction active layers have been of widespread interest in converting sunlight to electricity. Characterizing of the complex morphology at multiple length scales of polymer:nonfullerene small molecular acceptor (SMA) systems remains largely unexplored. Through detailed characterizations (hard/soft X-ray scattering) of the record-efficiency polymer:SMA system with a close analog, quantitative morphological parameters are related to the device performance parameters and fundamental morphology–performance relationships that explain why additive use and thermal annealing are needed for optimized performance are established. A linear correlation between the average purity variations at small length scale (≈10 nm) and photovoltaic device characteristics across all processing protocols is observed in ≈12%-efficiency polymer:SMA systems. In addition, molecular interactions as reflected by the estimated Flory–Huggins interaction parameters are used to provide context of the room temperature morphology results. Comparison with results from annealed devices suggests that the two SMA systems compared show upper and lower critical solution temperature behavior, respectively. The in-depth understanding of the complex multilength scale nonfullerene OSC morphology may guide the device optimization and new materials development and indicates that thermodynamic properties of materials systems should be studied in more detail to aid in designing optimized protocols efficiently.

Quantitative morphological parameters correlate well with the photovoltaic performance of six high-efficiency nonfullerene small molecular acceptors systems. Synergistic higher π–π coherence lengths and average domain purity result in over 12% efficiency fullerene-free organic solar cell (OSC) with a sequential treatment of solvent additive and thermal annealing. The work highlights the need for more detailed studies into the thermodynamics of OSCs.

Poly(3-hexyl thiophene) (P3HT) can be easily synthesized, demonstrating the large potential to decrease the cost in large-scale synthesis. Thus, the development of novel non-fullerene acceptor to match well with P3HT is urgent and necessary. The first benzotriazole-containing non-fullerene acceptor is designed and synthesized, and high open-circuit voltage (V _oc) of 1.02 V, fill factor (FF) of 0.70, and power conversion efficiency (PCE) of 5.24% are realized, which are remarkably higher than that of P3HT: [6,6]-phenyl-C₆₁-butyric acid methyl ester (PC₆₁BM) system (V _oc = 0.59 V, FF = 0.57, and PCE = 3.34%).

Reduced graphene oxide (rGO) is added in the [6,6]-Phenyl-C61-butyric acid methyl ester (PCBM) electron transport layer (ETL) of planar inverted perovskite solar cells (PSCs), resulting in a power conversion efficiency (PCE) improvement of ≈12%, with a hysteresis-free PCE of 14.5%, compared to 12.9% for the pristine PCBM based device. The universality of the method is demonstrated in PSCs based on CH₃NH₃PbI_3−xCl_x and CH₃NH₃PbI₃ perovskites, deposited through one step and two step spin coating process, respectively. After a comprehensive spectroscopic characterization of both devices, it is clear that the introduction of rGO in PCBM ETL results in an important increase of the ETL conductivity, together with reduced series resistance and surface roughness. As a result, a significant photoluminescence quenching of such perovskite/ETL is observed, confirming the increased measured short circuit current density. Transient absorption measurements reveal that in the rGO-based device, the relaxation process of the excited electrons is significantly faster compared to the reference, which implies that the charge injection rate is significantly faster for the first. Furthermore, the light soaking effect is significantly reduced. Finally, aging measurements reveal that the rGO stabilizes the ELT/perovskite interface, which results in the stabilization of perovskite crystal structure after prolonged illumination.

Planar inverted perovskite solar cells with high efficiency and ambient stability are fabricated based on a reduced graphene oxide (rGO) doped [6,6]-Phenyl-C61-butyric acid methyl ester (PCBM) electron transporting layer (ETL). The performance improvement is attributed to enhanced electron extraction, while the enhancement in the lifetime is due to the stabilization of the perovskite/ETL interface of the rGO doped device compared to the pristine.

Efficient monolithic perovskite/perovskite tandem solar cells are fabricated using two perovskite absorbers with complementary bandgaps. By employing doped organic semiconductors, an efficient and selective extraction of the charge carriers is ensured. This study demonstrates perovskite/perovskite tandem cells delivering a maximum efficiency of 18%, highlighting the potential of vacuum-deposited multilayer structures in overcoming the efficiency of single-junction perovskite devices.

The spin on a ferromagnetic Co surface can interact with the asymmetric orbital on an organometal halide perovskite surface, leading to an anisotropic magnetodielectric effect. This study presents an opportunity to integrate ferromagnetic and semiconducting properties through the Rasbha effect for achieving spin-dependent electronic functionalities based on thin-film design.

A novel-small molecular acceptor with electron-deficient 1,3,5-triazine as the core and perylene diimides as the arms is developed as the acceptor material for efficient bulk heterojunction organic solar cells with an efficiency of 9.15%.

A π-conjugated Lewis base is introduced into perovskite solar cells, namely, indacenodithiophene end-capped with 1.1-dicyanomethylene-3-indanone (IDIC), as a multifunctional interlayer, which combines efficient trap-passivation and electron-extraction. Perovskite solar cells with IDIC layers yield higher photovoltages and photocurrents, and 45% enhanced efficiency compared with control devices without IDIC.

The first homo-tandem non-fullerene organic solar cell enabled by a novel recombination layer which only requires a very mild thermal annealing treatment is reported. The best efficiency achieved is 10.8% with a V_oc over 2.1 V, which is the highest V_oc for double-junction organic solar cells reported to date.

New fiber-type piezoelectric nanogenerator devices consisting of radially aligned perovskite PbTiO₃ nanotubes are designed for energy harvesting from arbitrary mechanical motion. The free-standing fiber-type nanogenerators generate constant amount of electric power by bending or wind motion regardless of direction, thus, extending the possibility of their practical applications.

On page 10149, a simple and mass-scalable method, ultrafiltration, is proposed for achieving high-conductivity poly(3,4-ethylenedioxythiophene) (PEDOT): poly(4-styrenesulfonate) (PEDOT:PSS) by Y.-Y. Noh, J.-H. Kim, and co-workers. By effectively removing excess PSS and various reaction impurities using repeated 100 nm-poremembrane filtration, the purified PEDOT:PSS shows impressive conductivity and sheet resistance as high as 2000 S cm⁻¹ and 37.8 ± 4.5 Ω□⁻¹, respectively.

Hydrogen evolution reaction performance of MoS₂ can be enhanced through electric-field-facilitated electron transport. The best catalytic performance of a MoS₂ nanosheet can achieve an overpotential of 38 mV (100 mA cm⁻²) at gate voltage of 5 V, the strategy of utilizing the electric field can be used in other semiconductor materials to improve their electrochemical catalysis for future relevant research.