Hin-Lap Yip

City University of Hong Kong | CityU · Department of Materials Science and Engineering & School of Energy and Environment

Carbazole‐derived self‐assembled monolayers (SAMs) are promising materials for hole‐extraction layer (HEL) in conventional organic photovoltaics (OPVs). Here, a SAM Cbz‐2Ph derived from 3,6‐diphenylcarbazole is demonstrated. The large molecular dipole moment of Cbz‐2Ph allows the modulation of electrode work function to facilitate hole extraction a...

Metal halide perovskites, known for their pure and tunable light emission, near‐unity photoluminescence quantum yields, favorable charge transport properties, and excellent solution processability, have emerged as promising materials for large‐area, high‐performance light‐emitting diodes (LEDs). Over the past decade, significant advancements have b...

Perovskite solar cells (PSCs) are gaining significant attention as key players in the field of advanced photovoltaic technologies, attributed to their impressive efficiency metrics. Despite their advantages, achieving commercial viability for PSCs requires overcoming significant challenges, particularly in mitigating defects that trigger Shockley‐R...

Integrating semitransparent organic photovoltaics (ST‐OPVs) into building structures is a promising technology that serves aesthetic purposes while retaining window functionality, and it also facilitates solar energy harvesting and heat insulation. However, balancing power conversion efficiency (PCE), visible light transmittance (VLT), infrared rad...

Advances in improving the operational lifetime of highly efficient organic photovoltaic (OPV) and understanding photo-degradation mechanisms in molecular level are currently limited, especially on the promising inverted OPV, posing critical challenges to commercialization. Here, we demonstrate a radical scavenger (3-(3,5-Di-tert-butyl-4-hydroxyphen...

Wide‐bandgap perovskite sub‐cells (WPSCs), one of the most crucial components of perovskite‐based tandem solar cells (PTSCs), play a critical role in determining the performance of tandem devices. However, confined by the compromised crystallization properties of wide‐bandgap perovskites, WPSCs exhibit significantly lower efficiency than their theo...

While operational stability has evolved to be the primary issue for the practical applications of perovskite solar cells (PSCs), the understanding of the origins of device degradation is still limited. Hysteresis is known as a unique and significant feature of PSCs. The hysteresis behavior of the current density-voltage (J–V) curves, governed by th...

A strategically designed donor–acceptor (D‐A) block copolymer (PM6‐b‐PYIT) is introduced, as a compatibilizer to enhance the performance and stability of inverted organic solar cells (OSCs) consisting of a bulk heterojunction (BHJ) of PM6 and L8‐BO. The PM6‐b‐PYIT compatibilizer not only significantly boosts the power conversion efficiency from 16....

In recent years, the field of metal-halide perovskite emitters has rapidly emerged as a new community in solid-state lighting. Their exceptional optoelectronic properties have contributed to the rapid rise in external quantum efficiencies (EQEs) in perovskite light-emitting diodes (PeLEDs) from <1% (in 2014) to over 30% (in 2023) across a wide rang...

Miniaturized optical spectrometers could be of use in portable and wearable applications. Such devices have typically been based on arrays of photodetectors that provide distinct spectral responses or use complex miniaturized dispersive optics. However, these approaches often result in large centimetre-sized systems. Here we report a microsized opt...

Organic photovoltaic cells using Y6 non-fullerene acceptors have recently achieved high efficiency, and it was suggested to be attributed to the charge-transfer (CT) nature of the excitations in Y6 aggregates. Here, by combining electroabsorption spectroscopy measurements and electronic-structure calculations, we find that the charge-transfer chara...

Constructing low-dimensional/three-dimensional (LD/3D) per-ovskite solar cells can improve efficiency and stability. However, the design and selection of LD perovskite capping materials are incredibly scarce for inverted perovskite solar cells (PSCs) because LD perovskite capping layers often favor hole extraction and impede electron extraction. He...

Polymerization of Y6-type acceptor molecules leads to bulk-heterojunction organic solar cells with both high power-conversion efficiency and device stability, but the underlying mechanism remains unclear. Here we show that the exciton recombination dynamics of polymerized Y6-type acceptors (Y6-PAs) strongly depends on the degree of aggregation. Whi...

Operational stability is the main obstacle to the industrial applications of organic solar cells (OSCs). In this study, different degradation mechanisms under continuous simulated solar radiation are demonstrated for high‐performance non‐fullerene OSCs based on commonly used electron transport materials, i.e., ZnO and SnO2. The ZnO‐induced decompos...

Thermochromic perovskite smart windows (TPWs) are a cutting-edge energy-efficient window technology. However, like most perovskite-based devices, humidity-related degradation limits their widespread application. Herein, inspired by the structure of medical masks, a unique triple-layer thermochromic perovskite window (MTPW) that enable sufficient wa...

Effective passivation of defects at the buried interface between the perovskite absorber and hole‐selective layer (HSL) is crucial for achieving high performance in inverted perovskite solar cells (PSCs). Additionally, the HSL needs to possess compact molecular packing and intrinsic photo‐ and thermo‐stability to ensure long‐term operation of the d...

Zinc batteries hold promise for grid‐scale energy storage due to their safety and low cost. A key challenge for the field is identifying cathode materials that can undergo reversible redox reactions at the extreme potentials required for realizing high energy density devices. While organic materials have been extensively explored as cathode materia...

2PACz-modified NiO x thin films successfully replace PEDOT:PSS as hole transport layers, and achieve a high PCE of 16.7% in the PM6:Y6-based organic solar cells with simultaneous enhancement of efficiency, stability and reproducibility.

Self-assembled monolayers (SAMs) are key in enhancing the charge extraction interface of organic solar cells (OSCs), recently hitting a 20% power conversion efficiency (PCE). However, it is very challenging to...

Wide‐bandgap (WBG) perovskites have attracted considerable attention due to their adjustable bandgap properties, making them ideal candidates for top subcells in tandem solar cells (TSCs). However, WBG perovskites often face challenges such as inhomogeneous crystallization and severe nonradiative recombination loss, leading to high open‐circuit vol...

Uncontrolled sunlight entering through windows contributes to substantial heating and cooling demands in buildings, which leads to high energy consumption from the buildings. Recently, perovskite smart windows have emerged as innovative energy‐saving technologies, offering the potential to adaptively control indoor solar heat gain through their imp...

Zinc oxide (ZnO) is widely used as an electron transporting layer (ETL) for organic solar cells (OSCs). Here, a low‐cost commercial water/alcohol‐soluble fluorescent conversion agent, sodium 2,2′‐([1,1′‐biphenyl]−4,4′‐diyldivinylene)‐bis(benzenesulfonate) (CBS), is incorporated into ZnO to develop a novel organic‐inorganic hybrid ETL for high‐perfo...

The development of advanced perovskite emitters has considerably improved the performance of perovskite light-emitting diodes (LEDs). However, the further development of perovskite LEDs requires ideal device electrical properties, which strongly depend on its interfaces. In perovskite LEDs with conventional p-i-n structures, hole injection is gener...

Semitransparent organic solar cells (ST‐OSCs) can function as power‐generating windows due to their ability to allow visible light go‐through for human eyesight while absorbing low‐energy photons in the near‐infrared region for photocurrent generation. In this regard, effective ST‐OSCs with high light utilization efficiency (LUE) and color renderin...

Sequentially deposited organic solar cells (SD-OSCs) have attracted great attention owing to their ability in achieving more favorable, vertically phase-separated morphology to avoid the accumulation of counter charges at absorber/transporting layer interfaces. However, the processing of SD-OSCs is still quite challenging in preventing the penetrat...

State-of-the-art Y6-type molecular acceptors exhibit nanosecond excited-state lifetimes despite their low optical gaps (~1.4 eV), thus allowing organic solar cells (OSCs) to achieve highly efficient charge generation with extended near-infrared (NIR) absorption range (up to ~1000 nm). However, the precise molecular-level mechanism that enables low-...

Organic photovoltaics (OPVs) have achieved great progress in recent years due to delicately designed non-fullerene acceptors (NFAs). Compared with tailoring of the aromatic heterocycles on the NFA backbone, the incorporation of conjugated side-groups is a cost-effective way to improve the photoelectrical properties of NFAs. However, the modificatio...

Functional additives that can interact with the perovskite precursors to form the intermediate phase have been proven essential in obtaining uniform and stable α-FAPbI3 films. Among them, Cl-based volatile additives are the most prevalent in the literature. However, their exact role is still unclear, especially in inverted perovskite solar cells (P...

Monolithic perovskite/organic tandem solar cells (POTSCs) have significant advantages in next‐generation flexible photovoltaics, owing to their capability to overcome the Shockley–Queisser limit and facile device integration. However, the compromised sub‐cells performance challenges the fabrication of high‐efficiency POTSCs. Especially for all‐inor...

Wide‐bandgap perovskite sub‐cells (WPSCs)‐based tandem solar cells attract considerable interest because of their capability to surpass the Shockley–Queisser limit. Monolithic perovskite/organic tandem solar cells (POTSCs) integrating WPSCs and small‐bandgap organic sub‐cells (SOSCs) are famous compositions owing to their simple fabrication method...

Monolithic perovskite/organic tandem solar cells (POTSCs) have attracted increasing attention owing to ability to overcome the Shockley–Queisser limit. However, compromised sub‐cells performance limits the tandem device performance, and the power conversion efficiency (PCE) of POTSCs is still lower than their single‐junction counterparts. Therefore...

Following the 2nd release of the “Emerging PV reports,” the best achievements in the performance of emerging photovoltaic devices in diverse emerging photovoltaic research subjects are summarized, as reported in peer-reviewed articles in academic journals since August 2021. Updated graphs, tables, and analyses are provided with several performance...

Following the 2nd release of the “Emerging PV reports,” the best achievements in the performance of emerging photovoltaic devices in diverse emerging photovoltaic research subjects are summarized, as reported in peer‐reviewed articles in academic journals since August 2021. Updated graphs, tables, and analyses are provided with several performance...

Metal oxides are commonly employed as electron transport layers (ETLs) for n-i-p perovskite solar cells (PSCs), but the presence of surface traps and their mismatched energy alignment with perovskites limits the corresponding device performance. Therefore, the interfacial modification of ETLs by functional molecules becomes an important strategy fo...

Polymeric hole-transport materials (HTMs) play a critical role in determining the device performance and stability of perovskite solar cells (PVSCs). Fluorination on the conjugated backbone has been found to have the potential to modulate the molecular planarity, electrical property, and photovoltaic performance of the resulting polymer materials....

Comprehensive Summary High specific power or power to mass ratio is a critical concern of photovoltaic (PV) for aerospace applications. Organic solar cells (OSCs) have advantages such as high absorption coefficient, compatibility with flexible substrate, light‐weight, etc . Moreover, recently OSCs achieved power conversion efficiency (PCE) over 20%...

Visible and near-infrared (NIR) light dual-band photodetectors (PDs) have potential applications in signal detection, bioimaging, optical communications and safety monitoring. Herein, we report an ultrafast perovskite/organic heterojunction dual-mode PD with a voltage-modulated photoresponse range in visible and NIR spectra. The PD, comprising a pe...

Organic photovoltaics (OPVs) have progressed steadily through three stages of photoactive materials development: (i) use of poly(3-hexylthiophene) and fullerene-based acceptors (FAs) for optimizing bulk heterojunctions; (ii) development of new donors to better match with FAs; (iii) development of non-fullerene acceptors (NFAs). The development and...

Although the performance of blue perovskite LEDs (PeLEDs) has improved rapidly in the past few years, it still lags behind their green and red counterparts. One major cause of the inferior performance is the relatively low photoluminescence quantum yield (PLQY) of blue perovskite emitters due to more severe nonradiative recombination loss induced b...

Quasi‐2D perovskites show great promise for light‐emitting diodes owing to suppressed non‐radiative losses enabled by the energy funneling/cascading nanostructures. However, for red emission quasi‐2D perovskites, these ideal energy landscapes for efficient perovskite light‐emitting diodes (PeLEDs) can rarely be achieved due to detrimental aggregati...

Colloidal lead-halide perovskite nanocrystals (LHP NCs) have emerged over the past decade as leading candidates for efficient next-generation optoelectronic devices, but their properties and performance critically depend on how they are purified. While antisolvents are widely used for purification, a detailed understanding of how the polarity of th...

Tandem structures with different subpixels are promising for perovskite‐based multicolor electroluminescence (EL) devices in ultra‐high‐resolution full‐color displays; however, realizing excellent luminance‐ and color‐independent tunability considering the low brightness and stability of blue perovskite light‐emitting diodes (PeLEDs) remains a chal...

Non-fullerene acceptors (NFAs) are excellent light harvesters, yet the origin of their high optical extinction is not well understood. In this work, we investigate the absorption strength of NFAs by building a database of time-dependent density functional theory (TDDFT) calculations of ∼500 π-conjugated molecules. The calculations are first validat...

Solution processable quasi-2D (Q-2D) perovskite materials are emerging as a promising candidate for blue light source in full-color display applications due to their good color saturation property, high brightness, and spectral tunability. Herein, an efficient energy cascade channel is developed by introducing sodium bromide (NaBr) in phenyl-butyla...

See-through power windows are developed herein via a new design of semitransparent organic solar cells (ST-OSCs) that allows for the efficient utilization of spectrum-engineered solar photons from the visible to infrared range with both energy generation and saving features. These OSC-derived power windows simultaneously possess high color fidelity...

Polymer hole‐transport layers (HTLs) are critical components of inverted perovskite solar cells (IPVSCs). Triphenylamine derivatives PTAA (poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine]) and Poly‐TPD (poly[N,N′‐bis(4‐butylphenyl)‐N,N′‐bis(phenyl)benzidine]) have been widely adopted as hole‐transport materials due to their perovskite passivation ef...

Non-fullerene acceptors (NFAs) are excellent light harvesters, yet the origin of such high optical extinction is not well understood. In this work, we investigate the absorption strength of NFAs by building a database of time-dependent density functional theory (TDDFT) calculations of ~500 pi-conjugated molecules. The calculations are first validat...

As one of the core parts of two-terminal (2T) monolithic tandem photovoltaics, the interconnecting layers (ICLs) play a critical role in modulating the carrier transport and recombination between the sub-cells, and thus influencing the tandem device performance. Here, for the first time, the relationship between ICLs architecture and 2T monolithic...