Photovoltaic & Optoelectronic Device Group

Abstract:

All-inorganic halide perovskite materials have attracted significant interest for display applications because of their narrow bandwidths and high photoluminescence quantum yields. However, the development of blue-light-emitting perovskite materials has been slower than that of green- and red-light-emitting perovskites. In this study, we successfully produced single-halide CsPbBr3 nanoplatelets with a quantum confinement effect using ligand-assisted reprecipitation techniques. NaBr, an inorganic ligand with strong binding affinity (adsorption energy, -2.13 eV) and low steric hindrance, was used to prevent the continued growth of nanoplatelets. A series of experimental results demonstrate that CsPbBr3 nanoplatelets with a dense Na+ shell on the surface exhibit stable deep blue emission. UV chip-based light-emitting devices activated by these nanoplatelets demonstrated remarkable spectral stability as the current injection increased. Moreover, the synthesis process is conducted under simple conditions at room temperature, demonstrating potential for batch production.

Abstract:

Semi-transparent perovskite solar cells (ST-PSCs) have shown great potential in building-integrated photovoltaics. However, the performance of ST-PSCs is still far from achieving their true potential. Herein, a functional additive, [4-(trifluoromethyl)phenyl] sulfonyl chloride (TFBSC), is incorporated into the perovskite precursor solution to regulate the crystallization process and reduce defects in the perovskite films. The addition of TFBSC improves the perovskite film morphology and increases the charge carrier lifetime and photoluminescence quantum efficiency, compared with the control perovskite films. As a result, the champion device modified with TFBSC shows a power conversion efficiency (PCE) of 14.75% with a light utilization efficiency (LUE) of 3.92%, whereas the control device shows PCE and LUE values of 10.71% and 2.96%, respectively. Moreover, the unencapsulated TFBSC-modified device retains ∼90% of its initial PCE after 1500 h of storage under ambient conditions (relative humidity of ∼30%–40%). These findings could provide new avenues to develop high performance ST-PSCs for smart building applications.

Abstract:

Monolithic perovskite–organic tandem solar cells (POTSCs) have attracted considerable attention in recent years due to their compatible fabrication routes and advances in single-cell efficiencies. To further boost the performance of POTSCs, reducing the voltage losses that mainly arise from wide bandgap (WBG, >1.7 eV) perovskite subcells and interconnecting layers (ICLs) is critical. Here, a new ICL with a configuration of C60/YbO x /Au/MoO x is demonstrated for constructing the monolithic POTSC. The YbO x -based ICL benefits from an ohmic contact and high transparency, resulting in improved POSTC performance. The champion device presents a PCE of 23.2% owing to a high V OC of 2.11 V (approximately equal to the sum of individual V OC’s of the subcells) without compromising the short-circuit current density and fill factors. This work opens an avenue for developing efficient ICLs in POTSCs.

Abstract:

Metal halide perovskites could form the basis of future display technology due to their powerful optical properties. However, the commercialization of electroluminescent perovskites has been hindered by key challenges, including limited operational lifetime and instability in blue emission. Here we highlight the potential of perovskites in colour conversion displays. We examine the particular advantages of perovskite materials as colour conversion layers: narrow emission spectrum, high absorption coefficients, high-brightness operation, photon recycling and ease of manufacturing. We provide a framework for the development of RoHS (Restriction of Hazardous Substances)-compliant and colour-filter-free perovskite-based colour conversion displays and offer guidelines for commercialization. We also explore the potential of using perovskite colour conversion layers to create advanced augmented reality and virtual reality technologies.