A light-emitting element containing a fluorescent material and having high emission efficiency is provided. The light-emitting element contains the fluorescent material and a host material. The host material contains a first organic compound and a second organic compound. The first organic compound and the second organic compound can form an exciplex. The proportion of a delayed fluorescence component in light emitted from the exciplex is higher than or equal to 5%, and the delayed fluorescence component contains a delayed fluorescence component whose fluorescence lifetime is 10 ns or longer and 50 μs or shorter.

The present invention provides with an electron-accepting compound having a structure of the following formula (1): ##STR00001##

The present invention relates to a compound of formula (I) and an organic electronic device comprising a charge generation layer which comprises a compound of formula (I).

Described herein are solar cells, comprising: an active layer comprising a perovskite composition, wherein the perovskite composition comprises lead; and, a lead-absorbing material. In certain embodiments, the lead-absorbing material is an ion exchange material. The lead absorbing material helps prevent lead leakage in damaged solar cells and solar modules under severe weather conditions.

Organic devices comprising an organic semiconducting acceptor motif coupled to a donor motif. Examples include IOTIC-2F, ITOTIC-2F, COTIC-4F, and SiOTIC-4F as acceptor materials. The acceptor materials have narrow bandgap (1.1 eV-1.3 eV), strong near-IR absorption and high solar cell EQE in near infrared (IR) region. The acceptor materials may also be used as the absorbing/light sensitive region in an IR photodetector.

The present disclosure provides an organic electroluminescent device, a display substrate including the organic electroluminescent device, and a display apparatus including the display substrate. The organic electroluminescent device includes an anode, a cathode, and a light emitting layer between the anode and the cathode, wherein a hole transport layer is provided between the anode and the light emitting layer and includes a hole transport material and a P-type doping material, electrons of the highest occupied molecular orbit of the P-type doping material are excitable to the lowest unoccupied molecular orbit of the P-type doping material under the excitation of light to cause an electron transfer reaction from the highest occupied molecular orbit of the hole transport material to the highest occupied molecular orbit of the P-type doping material.

Provided is a light-emitting element including a first organic compound, a second organic compound, and a guest material. The LUMO level of the first organic compound is lower than that of the second organic compound. The HOMO level of the first organic compound is lower than that of the second organic compound. The LUMO level of the guest material is higher than that of the first organic compound. The HOMO level of the guest material is higher than that of the second organic compound. An energy difference between the LUMO level and the HOMO level of the guest material is larger than an energy difference between the LUMO level of the first organic compound and the HOMO level of the second organic compound. The guest material can convert triplet excitation energy into light emission. The combination of first organic compound and the second organic compound can form an exciplex.

Provided are a light-emitting device and a light-emitting apparatus including the same. The light-emitting device includes a first electrode, a second electrode facing the first electrode, and an interlayer between the first electrode and the second electrode and including an emission layer; and optionally, a capping layer on the second electrode, wherein i) the second electrode includes a first material, or ii) when the light-emitting device includes the capping layer, at least one selected from the second electrode and the capping layer includes the first material, and the first material has a refractive index in a range of about 1.6 to about 2.4 in a wavelength band of blue light, green light, and red light, and a band gap of the first material is more than about 1.5 eV.

An object is to provide a light-emitting element which uses a plurality of kinds of light-emitting dopants and has high emission efficiency. In one embodiment of the present invention, a light-emitting device, a light-emitting module, a light-emitting display device, an electronic device, and a lighting device each having reduced power consumption by using the above light-emitting element are provided. Attention is paid to Förster mechanism, which is one of mechanisms of intermolecular energy transfer. Efficient energy transfer by Förster mechanism is achieved by making an emission wavelength of a molecule which donates energy overlap with the longest-wavelength-side local maximum peak of a graph obtained by multiplying an absorption spectrum of a molecule which receives energy by a wavelength raised to the fourth power.

By introducing new concepts into a structure of a conventional organic semiconductor element and without using a conventional ultra thin film, an organic semiconductor element is provided which is more reliable and has higher yield. Further, efficiency is improved particularly in a photoelectronic device using an organic semiconductor. Between an anode and a cathode, there is provided an organic structure including alternately laminated organic thin film layer (functional organic thin film layer) realizing various functions by making an SCLC flow, and a conductive thin film layer (ohmic conductive thin film layer) imbued with a dark conductivity by doping it with an acceptor and a donor, or by the like method.