Ivy Mawusi Asuo

Passivation of surface defects at the interface between perovskite absorber layers and charge transport layers is important for reducing ion migration and nonradiative recombination, thereby improving the performance of perovskite photovoltaics. In indoor photovoltaics, the bandgap of the perovskite absorber layer must be engineered to optimize device performance, typically through compositional tuning of the precursor materials. Passivation becomes even more relevant when light intensity levels are low, as fewer charge carriers are generated and recombination can be much more detrimental. Herein, we simultaneously apply composition and anti-solvent engineering, varying bromine content in the perovskite and using chlorobenzene or dichlorobenzene, with phenethylammonium salts as interfacial passivators to (i) increase the crystallinity and grain sizes of the perovskite absorber layer, (ii) form a quasi-2D/3D perovskite heterojunction to passivate surface defects, and (iii) demonstrate light-intensity-dependent stability behavior. The optimized perovskite indoor photovoltaic devices with an aperture area of 0.093 cm2, using dichlorobenzene as the anti-solvent and phenethylammonium bromide as the passivation salt, achieved an improved efficiency of 36.2% with a power output of 112.2 μW cm−2, a fill factor of 76.5%, an open-circuit voltage of 1.04 V, and a short-circuit current density of 141.28 μA cm−2 under 1000 lux.

Metal halide perovskite indoor photovoltaics (IPVs) are the top contenders in terms of efficiency among emerging IPV technologies. The state‐of‐the‐art perovskite IPVs have already achieved reported efficiencies above 44%, indicating their significant potential. However, only a small percentage of reports discuss stability measurements, with approximately 7% adopting the International Summit on Organic PV Stability (ISOS) protocol for stability evaluation. A standard for the stability assessment of emerging thin film IPVs still lags. This research area remains largely unexplored, yet it is essential to the commercialization of IPV technologies. This review focuses on perovskite‐based IPVs, with an emphasis on device stability. It provides discussions of the origins of degradation in perovskite materials and their corresponding IPV devices. This is followed by an overview of various structure–property–stability strategies, including compositional, interface, and device design engineering for perovskite materials to improve their performance. Finally, the review outlines some existing stability test protocols that could apply to perovskite IPVs, including addressing mitigation issues, such as encapsulation, draws the attention of researchers in the field, and calls for the development of standardized stability test protocols for perovskite IPVs and for understanding how these tests correlate with actual indoor lifespans to enable the commercialization of perovskite IPVs.

A simple spin-coating speed-tuning approach for safer-solvent ambient-processed perovskite thin film can lead to semitransparent solar cells. The study compares DMSO with the traditional DMF:DMSO for semitransparent perovskite thin films and devices.

Examining A-site cation modification and anti-solvent effects on Cs-based perovskites reveal that using toluene coupled with a small amount of FA⁺ affects the optoelectronic, structural, and morphological properties of the thin films and device.

Hole-transporting materials (HTMs) are crucial for charge separation in perovskite solar cells (PVSCs). Besides possessing suitable HOMO/LUMO energies, HTMs should ideally be hydrophobic to protect the perovskites from atmospheric moisture to enhance device stability. We designed two fluorene-core D–π–D-type organic HTMs (V1 and V2), consisting of either 4,4′-methoxy triphenylamine (V1) or N-phenyl-3,6-methoxy carbazole (V2) as the peripheral donor moiety. Optoelectronic characterization and density functional theory calculations confirmed the intramolecular charge transfer within these new HTMs. UPS and REELS analyses revealed favorable HOMO–LUMO energy level alignment of V1 and V2 with the work functions of MAPbI₃ and gold electrode for effective charge extraction. TRPL and transient absorption studies commendably explained better quenching of perovskite's luminescence by V1 over V2, suggesting a better interfacial contact of V1 with the perovskite layer. Accordingly, the PVSCs with V1 and V2 as HTMs in an architecture ITO/SnO₂/MAPbI₃/HTM(V1 or V2)/Au demonstrated power conversion efficiency (PCE) of 14.05% and 12.73% respectively. Also, the device with V1 retains 75% of its initial efficiency for more than 480 hours. The contact angle measurements revealed the strong hydrophobicity of both alkylated fluorene molecules (V1 and V2), and impedance spectroscopy measurements further revealed higher R_rec values for these HTMs, indicating improved charge transport and reduced recombination losses. These findings demonstrate the potential of the newly developed hydrophobic fluorene-based HTMs for achieving long-lasting performance in PVSCs.

Ambient solution-processed halide perovskite thin films are susceptible to oxygen and moisture. Composition and morphology control of the films via anti-solvents treatment, i.e. , DCB, EtOH, and CB affect their crystallization and solar cell performance.

In this study, we have fabricated and characterized three different configurations of photodetectors with digital inkjet printing techniques on different types of silicon substrates, such as pristine n-type silicon and chemically nanostructured n-type silicon, with and without Ag nanoparticle-induced surface-plasmon enhancement. Among these three comparison batches, digitally printed devices on chemically nanostructured n-type silicon with Ag nanoparticle-induced enhancement yield the highest photocurrent enhancement factor of 920×, the lowest rise and decay times of τr = 176 ms and τd = 98 ms, respectively, and the highest responsivity of 24.8 mA W−1 at wavelengths ranging from 380 to 700 nm. Most importantly, we demonstrate that these devices are highly stable after fabrication, losing less than 3% of their efficiency over 60 days under ambient conditions. We firmly believe that this simple device architecture and effective digital fabrication process are most promising for the realization of efficient, stable, and low-cost photodetectors fabricated at large scales.

A hybrid photodetector fabricated with a halide perovskite and silicon nanowire (SiNW) heterojunction for broadband detection ranging from near‐ultraviolet to near‐infrared is reported. The device fabrication is conducted by directly coating chemically etched vertical SiNW arrays with perovskite thin films and nanofibers produced from liquid precursors. The optimized perovskite thin film/SiNW heterojunction‐based device under 532 nm illumination exhibits excellent spectral responsivity of 13 A W⁻¹, high specific detectivity reaching 10¹³ Jones at 0.3 V external bias, and fast rise/fall times of 22.2/17.6 μs. The device shows very good stability under ambient conditions, even after 30 days of storage. Overall, this simple, all‐solution‐based hybrid photodetector offers great potential for the future integrated optoelectronic devices.

Organic hole‐transporting materials (HTM) are widely used for high‐efficiency solar cells. However, compared with their inorganic counterparts, these materials are often expensive and require complex synthesis methods and the addition of costly dopants to improve their performance. In addition, exposure to the ambient environment affects the chemical stability of some organic materials as well as their device characteristics. Herein, an all‐ambient fabrication method is used to develop a CuSCN layer as an alternative to the conventional Spiro‐OMeTAD HTM. CuSCN thin films are incorporated into both solar cells and photodetectors to study their effect on the optoelectronic properties of these devices. For the solar cells made with CuSCN, a power conversion efficiency of 14.3% is achieved, with remarkable ambient‐stability without encapsulation. Regarding the photodetectors with CuSCN, high‐specific detectivity up to 10¹² Jones is exhibited. Solution‐processed devices exhibit overall impressive performances and represent an essential step toward large‐scale fabrication of efficient, stable, facile, and inexpensive perovskite‐based optoelectronic technologies.