Boron-Doped Molecules for Optoelectronics

Doping of polycyclic aromatic hydrocarbons (PAHs) with boron atoms is an effective method to fine-tune the optoelectronic properties of π-conjugated materials. B,N-doped PAHs are effective blue thermally activated delayed fluorescence (TADF) emitters for organic light-emitting diodes (OLEDs). These molecules may ultimately provide a solution for the much sought-after stable and highly efficient pure-blue OLEDs. Organic field-effect transistors with high mobilities can be achieved using B-doped PAHs because the empty pz orbital of boron facilitates charge-carrier transport. Incorporation of B–N units into π-conjugated polymers dramatically alters their HOMO/LUMO energies, making them excellent donor/acceptor materials for organic photovoltaics. The captodative B–N strategy is a promising approach to enhance the diradical character of acenes and achieve new singlet-fission chromophores. Boron-containing π-conjugated systems are an emerging class of materials for important energy-conversion applications. Because of its electron-deficient nature, embedding boron atoms into an organic material introduces electron-accepting centers that impart unique optoelectronic functions and greatly enhance performance in energy-conversion devices such as organic light-emitting diodes (OLEDs), organic photovoltaics (OPVs), and organic field-effect transistors (OFETs). This review covers recent advances in boron-doped molecules for optoelectronics, focusing on their superior performance relative to conventional carbon analogs. Future directions and opportunities for improvement of organoboron-based materials in these areas of research are discussed. Boron-containing π-conjugated systems are an emerging class of materials for important energy-conversion applications. Because of its electron-deficient nature, embedding boron atoms into an organic material introduces electron-accepting centers that impart unique optoelectronic functions and greatly enhance performance in energy-conversion devices such as organic light-emitting diodes (OLEDs), organic photovoltaics (OPVs), and organic field-effect transistors (OFETs). This review covers recent advances in boron-doped molecules for optoelectronics, focusing on their superior performance relative to conventional carbon analogs. Future directions and opportunities for improvement of organoboron-based materials in these areas of research are discussed. the combined action of an electron-withdrawing (captor) and an electron-releasing (donor) substituent on a radical center to improve stabilization. a chromaticity diagram represents the mapping of human color perception as defined by two CIE parameters x and y. an electron acceptor usually contains an empty atomic orbital that can accept electrons such as a three-coordinate boron center or electron-deficient groups like sulfone, phosphine oxide, or electronegative heterocycles (e.g., triazole or aromatic rings decorated with electron-withdrawing groups). an electron donor contains lone electrons (e.g., arylamines) or electron-rich aromatic units (e.g., thiophene) from which an electron can be removed. the ratio of the number of photons emitted externally to the number of electrons injected into a device. the highest-energy molecular orbital containing electrons. a radiationless process involving a transition between two electronic states with different state spin multiplicities (e.g., between the S1 and T1 state). defined as number of photons coming out of a device per number of photons generated within a device. the lowest-energy molecular orbital capable of receiving an electron. a type of photoluminescence. When an electron is promoted from the ground state (S0, with a spin multiplicity of zero) to the excited state by absorbing energy, it may relax back to the ground state by emitting a photon from either a singlet excited state (e.g., S1, in which all electrons are all paired with a spin multiplicity of zero) or a triplet excited state, (e.g., T1, in which there are two non-paired electrons with a spin multiplicity of three). Light emission resulting from a transition from a singlet excited state is fluorescence, whereas that from a triplet excited state is termed phosphorescence. defined as the number of photons emitted per number of absorbed photons. hydrocarbon compounds comprising multiple fused aromatic rings. Common examples are naphthalene, pyrene, and pentacene.