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We prepared ternary organic solar cells (OSCs) by incorporating the medium wavelength absorption polymer PSEHTT into the PM6:L8-BO binary system. The power conversion efficiency (PCE) is improved from 15.83% to 16.66%. Although the fill factor (FF) is slightly reduced, the short-circuit current density (JSC) and open-circuit voltage (VOC) are significantly increased at the same time. A small amount of PSEHTT has a broad absorption spectrum in the short wavelength region and has good compatibility with PM6, which is conducive to fine-tuning the photon collection and improving the JSC. In addition, the highest occupied molecular orbital (HOMO) energy level of PSEHTT is deeper than that of PM6, which broadens the optical bandgap. This study provides an effective method to fabricate high-performance ternary OSCs by using a lower concentration of PSEHTT with PM6 as a hybrid donor material, which ensures a better surface and bulk morphology, improves photon collection, and broadens the optical bandgap. [ABSTRACT FROM AUTHOR]

The perovskite photovoltaic field has developed rapidly within a decade. In particular, formamidinium (FA)‐rich perovskite allows a broad absorption spectrum, and is considered to be one of the most promising perovskite materials. Great progress has been achieved, and most recorded high‐efficient perovskite solar cells (PSCs) used the FA‐rich perovskite light absorption layer. However, the black α‐phase formamidinium lead iodide (FAPbI3) perovskite easily transforms into an undesirable δ‐phase at a low temperature. Thus, researchers have put a lot of effort into deeply understanding the phase transformation and stabilization mechanism of FA‐rich perovskite. Herein, the fundamental physical properties of FAPbI3 materials, including crystal structure, phase‐transition temperature, charge‐carrier dynamics, etc. are summarized, and establish a complete phase evolution with temperature by reviewing previous reports. The intrinsic and external factors are subsequently discussed for influencing the stability of FAPbI3 perovskite and the remarkable breakthroughs of FA‐rich PSCs in recent years are reviewed. Moreover, a series of strategies to stabilize FA‐rich perovskite is summarized, including but not limited to compositional engineering, passivating engineering, processing engineering, and strain engineering. Finally, several new viewpoints are provided for improving the efficiency and stability of PSCs. This review may be regarded as a reference project for preparing high‐efficient and stable perovskite photovoltaic devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ternary PSCs were fabricated with PBDB-TF as third component materials. • The improvement of charge dynamics process of ternary photoactive layer by ternary strategy. • The improved exciton-dissociation at the donor–blend acceptor interface. In this manuscripts, a ternary polymer solar cells (PSCs) are fabricate with two "D18-series" donor (D18-Cl and D18) as blend donor and T6 as acceptor. The effects of D18-Cl and D18 in ternary PSC on the film morphology, photoelectronic properties and charge carrier dynamics were systematically investigated. By finely adjusting the D18 content, a power conversion efficiency (PCE) of 16.66 % is achieved in the optimized ternary PSCs with 35 wt% D18 in donor, resulting from significantly improved short-circuit-current density (J SC) of 26.80 mA cm−2 in comparison with those of D18-Cl:Y6 binary PSCs. The J SC of ternary PSCs monotonously increase along with the incorporation of D18, indicating that D18 is comprehensively optimal short wavelength photon harvesting compared with D18-Cl. Both D18-Cl and D18 are shown similar highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels, which is beneficial to efficient charge transport at the blend donor domain. Our work indicates that the blend of D18-Cl and D18 as blend donor and Y6 as electron acceptor to boost photovoltaic performance in the ternary PSCs. [ABSTRACT FROM AUTHOR]

All-inorganic CsPbBr 3 perovskite has triggered great interests in photovoltaic field owing to its superior stability. However, the uncontrollable CsPbBr 3 film growth in solution always leads to a poor film quality with low phase-purity as well as many surface and bulk defects. Herein, we demonstrate an environmentally friendly non-solution route to fabricate high-quality CsPbBr 3 films for carbon-based planar perovskite solar cells. By precisely tuning the thickness ratio of the evaporated CsBr to PbBr 2 precursors (r), the dominant phase conversion of the cesium lead bromide perovskites from PbBr 2 -rich CsPb 2 Br 5 (r ≤ 12:7) to CsPbBr 3 (r = 12:8), and further to CsBr-rich Cs 4 PbBr 6 (r ≥ 12:9) are achieved. The optimized CsPbBr 3 perovskites are highly phase-pure and crystallized with ultra-high light absorption ability. The as-prepared CsPbBr 3 films also exhibit a dense and uniform morphology with large grain sizes and monolayer-vertical aligned grains. The corresponding devices deliver a champion PCE of 7.58%, which is an excellent efficiency among carbon-based CsPbBr 3 cells with evaporated CsPbBr 3 light absorbers. The large-area (1 cm2) devices also achieve an efficiency of 6.21%. Moreover, the unencapsulated CsPbBr 3 devices present superior moisture and thermal stabilities. Our work provides a facile approach to fabricate high-quality and large-area CsPbBr 3 films for highly efficient solar cells, light-emitting diodes and photodetectors. Image 1 • A sequential evaporation method is devised to prepare high-quality CsPbBr 3 films. • An excellent PCE of 7.58% is achieved for carbon-based CsPbBr 3 PSCs. • A PCE of 6.21% is obtained for large-area devices with an active area of 1 cm2. • Superior moisture and thermal stabilities are obtained for the devices. • The whole production costs of the devices are very low. [ABSTRACT FROM AUTHOR]