Hole transporting layer plays a crucial role to realize high efficiency and long lifespan by balancing the charge carrier into the desired recombination zone.

Organic light emitting diodes (OLEDs) have been well known for their potential usage in the lighting and display industry. The device efficiency and lifetime have improved considerably in the last three decades. However, for commercial applications, operational lifetime still lies as one of the looming challenges. In this review paper, an in-depth description of the various factors which affect OLED lifetime, and the related solutions is attempted to be consolidated. Notably, all the known intrinsic and extrinsic degradation phenomena and failure mechanisms, which include the presence of dark spot, high heat during device operation, substrate fracture, downgrading luminance, moisture attack, oxidation, corrosion, electron induced migrations, photochemical degradation, electrochemical degradation, electric breakdown, thermomechanical failures, thermal breakdown/degradation, and presence of impurities within the materials and evaporator chamber are reviewed. Light is also shed on the materials and device structures which are developed in order to obtain along with developed materials and device structures to obtain stable devices. It is believed that the theme of this report, summarizing the knowledge of mechanisms allied with OLED degradation, would be contributory in developing better-quality OLED materials and, accordingly, longer lifespan devices.

In this work, a novel series of phenothiazine and phenoxazine substituted fluorene core-based solution-processable nanotextured HTMs was reported. Of these, the phenoxazine material showed a superior performance in phosphorescent yellow and TADF green OLEDs.

We present a strategy for developing an in-depth understanding of the synergy between triplet energy (E T) and structural composition of molecular hosts for organic light-emitting diodes (OLEDs) initially through virtual screening of molecules with the help of density functional theory (DFT) followed by experimental validation. Four solution-processable hosts belonging to two groups of positional isomers based on a similar constitutional core have been theoretically screened and employed in OLED devices. Remarkably, substitutional change of the cyano moiety from para- to meta-position restricts the orbital overlap between the cyano group and other parts of the molecule, which enhances the E T of the compound, leading to better device performance. An excellent increment in the power efficacy of the OLED device has been observed when a para-cyano (E T = 2.59 eV)-based host is replaced with its meta-counterparts (E T = 2.72 eV). The constitutional factors of the molecules also highly influenced the efficacy as we observed around 1.5 times increment in the power efficacy when one phenyl unit of the host AT110 is replaced by one carbazole functionality in AT111 although both hosts possess similar E T (2.72 eV). The solution-processed fabricated best green device exhibited a maximum power efficacy of 72.3 lm W–1 and current efficacy of 69.9 cd A–1 with driving voltage of 2.8 V.

A series of electron deficient perylene bisimides (PBIs) bearing 3,4,5-tridecylphenyl substituents on the imide N-atoms and bay-annulated with the hetero atoms like N, S, Se in the bay positions of...