Amino acid, with amino, carboxyl, and other functional groups in one molecule, is proposed as an effective multisite passivator for perovskite solar cells (PSCs). However, the chirality‐induced difference in photovoltaic properties of PSCs caused by subtle changes of the molecular environment between enantiomers of the amino acid has received almost no attention. Herein, for the first time, l‐ and d‐cysteine are introduced into carbon‐based fully printable mesoscopic PSCs as additives and 17.41 and 15.12% of power conversion efficiency are obtained, respectively. The essential causes of the differences in photoelectric conversion performances are deeply explored within a density‐functional theory (DFT) framework and relative photophysical characterization. DFT reveals that the enhancement of negative surface electrostatic potential around the carboxyl group is due to the chiral molecular environment favoring intramolecular charge transfer with l‐cysteine, strengthening the coordination to undercoordinated Pb2+ (halide vacancy) defects. In addition, the advantages of the chiral environment of l‐cysteine are also reflected in the inhibition of nonradiative recombination, perovskite crystallization, stability, and light capture, etc. It opens up a novel research pathway extending passivation mechanism from functional groups to the molecular environment.

Although ionic conjugated passivation systems, such as ionic liquids (ILs), have been used to passivate perovskite in carbon‐based printable mesoscopic perovskite solar cells (FP‐PSCs), their tautomerism process and synergistic effect of multifunctional groups have not yet caused enough attention. In this work, a series of novel ILs including 1‐allyl‐3‐methylimidazole tetrafluoroborate ([AMIm]BF4) and 1‐benzyl‐3‐methylimidazole tetrafluoroborate ([BzMIm]BF4) used as passivants for FP‐PSCs are reported. Combining Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculation, it is found that one of its tautomers (positive ion at the near end N atom of conjugated side chain) plays a key role on dual‐site simultaneous passivation. As the conjugation degree of side chain increases from allyl to benzyl, it not only effectively inhibits the non‐radiative charge recombination, but also reduces the passivation adsorption energy and increases the charge transfer rate. A high efficiency of 16.87% has been achieved with a high FF (>0.7), a Jsc of 23.88 mA cm–2 value and Voc value up to 1.0 V, by using the “tautomeric dual‐site passivation” strategy.

For carbon‐based fully printable mesoscopic perovskite solar cells (FP‐PSCs), due to the serious interfacial defects formed in the uncontrollable crystallization process, modifying the interface between perovskite and electron transport layer is an effective way to enhance their photovoltaic performance. Herein, ultrathin ZrO2 is deposited on the mesoporous TiO2 surface by using spray pyrolysis, and Zr4+ intercalates into the TiO2 surface lattice and works together with Ti4+ and O2− ions. Thanks to this surface lattice perturbation of Zr4+, the reduction of surface oxygen vacancies of TiO2 (electron transport layer) decreases the density of defective states at the TiO2–perovskite interface inhibiting the Shockley–Read–Hall recombination (nonradiative recombination) in the charge cross‐interface transfer. Furthermore, both the open‐circuit voltage and short‐circuit current density are improved significantly. Based on perovskite Cs0.05(FA0.92MA0.08)0.95Pb(I0.92Br0.08)3 for carbon‐based FP‐PSCs, a high power conversion efficiency of 17.81% is obtained. It provides a novel idea and technology for efficient interfacial modification of the electron transport layer for FP‐PSCs.

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All solidification is the only way for dye‐sensitized solar cells (DSSCs) to achieve commercial application. At present, the intricate and expensive approaches such as vapor deposition used for DSSCs based on hole transport materials are unsuitable for the development of large‐scale all‐solid‐state devices. Herein, a new avenue for the evolution of all solid‐state DSSCs through dissolving the I−/I3− redox couple in commercial UV glue and then solidifying under UV light as electron transport materials is put forward. Not only does this device show superior stability (the power conversion efficiency (PCE) can be maintained more than 95% after 1000 h), but also an optimum PCE of 6.15% (short‐circuit photocurrent density = 11.93 mA cm−2, open‐circuit voltage = 683 mV, fill factor = 0.75) is obtained. It must be the best choice for the future development of all‐solid‐state DSSC device.