Toward Highly Efficient Solid‐State White Light‐Emitting Electrochemical Cells: Blue‐Green to Red Emitting Cationic Iridium Complexes with Imidazole‐Type Ancillary Ligands

Abstract

Using imidazole‐type ancillary ligands, a new class of cationic iridium complexes (1–6) is prepared, and photophysical and electrochemical studies and theoretical calculations are performed. Compared with the widely used bpy (2,2′‐bipyridine)‐type ancillary ligands, imidazole‐type ancillary ligands can be prepared and modified with ease, and are capable of blueshifting the emission spectra of cationic iridium complexes. By tuning the conjugation length of the ancillary ligands, blue‐green to red emitting cationic iridium complexes are obtained. Single‐layer light‐emitting electrochemical cells (LECs) based on cationic iridium complexes show blue‐green to red electroluminescence. High efficiencies of 8.4, 18.6, and 13.2 cd A−1 are achieved for the blue‐green‐emitting, yellow‐emitting, and orange‐emitting devices, respectively. By doping the red‐emitting complex into the blue‐green LEC, white LECs are realized, which give warm‐white light with Commission Internationale de L'Eclairage (CIE) coordinates of (0.42, 0.44) and color‐rendering indexes (CRI) of up to 81. The peak external quantum efficiency, current efficiency, and power efficiency of the white LECs reach 5.2%, 11.2 cd A−1, and 10 lm W−1, respectively, which are the highest for white LECs reported so far, and indicate the great potential for the use of these cationic iridium complexes in white LECs.

Highly Stable and Efficient Light-Emitting Electrochemical Cells Based on Cationic Iridium Complexes Bearing Arylazole Ancillary Ligands

“…23 They are also competitive with the top peak efficiencies (18.6 cd A ) obtained by He et al under constant voltage operation that leads to higher peak luminances and higher currents accompanied by a strong reduction in lifetime. 38 Interestingly, the exceptional efficiency found for the [3][PF 6 ] LEC (9.2 cd A -1 ) is much higher than the efficiency previously obtained for this complex under voltage scan (1.5 cd A…”

A long-persistent phosphorescent chemosensor for the detection of TNP based on CaTiO3:Pr3+@SiO2 photoluminescence materials

“…21,22 On the other hand, when using an optical sensing technology, a large background uorescence signal will cause a negative impact during detection process, 23,24 Compared with uorescent materials, phosphorescent materials can eliminate the interference from short-lived uorescent background by using time-resolved technology, with added advantages of high luminescence efficiency, and good photo and thermal stabilities. [25][26][27] Nevertheless, so far there are few reports about detecting nitroaromatic explosives by means of phosphorescence method.…”

Highly Efficient Light-Emitting Electrochemical Cells (LECs) from Host-Guest Cationic Iridium(III) Complexes

“…Recently, Yong Qiu demonstrated a warm-white light LECs with the peak external quantum efficiency, current effi- * This paper was presented at the 12th International Conference on Atomically Controlled Surfaces, Interfaces and Nanostructures (ACSIN-12) in conjunction with the 21st International Colloquium on Scanning Probe Microscopy (ICSPM21), Tsukuba International Congress Center, Tsukuba, Japan, November 4-8, 2013. † Corresponding author: rukkiat_j@hotmail.com ciency, and power efficiency reach 5.2%, 11.2 cdA −1 , and 10 lmW −1 [12]. In this article, we show the highly efficient host-guest OLED devices based on a charged iridium(III) complex by the insertion of the TPBi and LiF layers.…”