The hole transporting layer (HTL) plays an important role in realizing efficient and stable perovskite solar cells (PSCs). In spite of intensive research efforts toward the development of HTL materials, low‐cost, dopant‐free hole transporting materials that lead to efficient and stable PSCs remain elusive. Herein, a simple polycyclic heteroaromatic hydrocarbon‐based small molecule, 2,5,9,12‐tetra(tert‐butyl)diacenaphtho[1,2‐b:1′,2′‐d]thiophenen, as an efficient HTL material in PSCs is presented. This molecule is easy to synthesize and inexpensive. It is hydrophobic and exhibits excellent film‐forming properties on perovskites. It has unusually high hole mobility and a desirable highest occupied molecular orbital energy level, making it an ideal HTL material. PSCs fabricated using both the n‐i‐p planar and mesoscopic architectures with this compound as the HTL show efficiencies as high as 15.59% and 18.17%, respectively, with minimal hysteresis and high long term stability under ambient conditions.

The addition of phenyllithium to a polycyclic quinone, 9,11,12,21,22,24-hexaphenyltetrabenzo[a,c,n,p]hexacene-10,23-dione (10), followed by SnCl -mediated reduction of the diol intermediate, yielded 9,10,11,12,21,22,23,24-octaphenyltetrabenzo-[a,c,n,p]hexacene (4). Crystallographic analysis of hexacene 4 showed it to possess a longitudinal twist of 184°, which was in good agreement with AM1 calculations. In addition to being the most twisted acene synthesized to this point, compound 4 contains within its substructure the most twisted naphthalene, anthracene, tetracene, and pentacene moieties described.

SCLC hole mobilities up to 8.72 Â 10 À2 cm 2 V À1 s À1 , amongst the highest reported hole mobility values for solution-processed smallmolecule organic semiconductors, are obtained from thermally annealed device-sized thin films of a thiophene-containing polycyclic aromatic hydrocarbon.Charge carrier (hole or electron) mobility is one important parameter affecting the performance of organic electronic/ optoelectronic devices including organic solar cells. 1 The highest hole mobilities (up to $45 cm 2 V À1 s À1 ) for organic semiconductors have been demonstrated on macroscopic, highly ordered, single crystals of conjugated molecules. 2,3 Benetting from the fast advancement of materials chemistry, the hole mobilities of organic-semiconductor thin lms, which are usually prepared by spin-coating or vacuum deposition, have also steadily increased to as high as 12 cm 2 V À1 s À1 . 4,5 Almost all of these high hole mobility values have been obtained by the eld effect transistor (FET) method. Compared to the FET method, which measures the mobility parallel to the electrodes under inuence of a gate bias, the space charge limited current (SCLC) method measures the mobility perpendicular to the electrodes. 6 The SCLC mobility is thus more relevant to solar cells. The FET and SCLC techniques are two of the most widely used methods to investigate charge carrier mobility in organic compounds. The SCLC mobility of organic-semiconductor thin lms is oen lower by a few orders of magnitude than their FET mobility. 6 Despite a few reports of high SCLC mobilities (up to 1.4 cm 2 V À1 s À1 ) measured in mesoscopic/microscopic areas of discotic liquid crystalline conjugated molecules, 3 the SCLC mobilities of macroscopic organic-semiconductor thin lms are generally much lower, ranging from 10 À6 to 10 À4 cm 2 V À1 s À1 . 6-8Among myriads of conjugated molecules, polycyclic aromatic hydrocarbons (PAHs) have drawn the most interest and have been widely investigated for electronic applications. 9-16 Their oen planar or near-planar geometry and extended p-delocalization can induce strong p-p stacking resulting in potentially high charge carrier mobility along the stacked PAH column. 11,15,16 Indeed, the majority of the reported highest SCLC hole mobilities are obtained from PAHs. 2,3 A thiophene-containing fused PAH, namely 2,5,9,12-tetra(tertbutyl)diacenaphtho[1,2-b:1 0 ,2 0 -d]thiophene (DAT) (1) (Fig. 1a), was rst synthesized approximately een years ago but has not drawn much attention. 17,18 Nor have its electronic properties/ Fig. 1 (a and b) Structures of compounds 1 and 2. Energy-minimized geometries of 1 (c and e) and 2 (d and f) from different views obtained using DFT calculations at the B3LYP/6-31G(d) level. † Electronic supplementary information (ESI) available: Experimental details; synthesis and characterization of 1 and 2; visualized LUMO+1, LUMO, HOMO and HOMOÀ1 orbitals of the energy-minimized conformers; UV-vis absorption and orescence emission spectra; cyclic voltammograms; DSC thermograms. See

Seven longitudinally twisted acenes (an anthracene, two tetracenes,t hree pentacenes, and ah exacene) have been synthesizedb yt he addition of aryllithium reagents to the appropriate quinone precursors, followed by SnCl 2 -mediatedr eductiono ft heir diol intermediates, and severalo ft hese acenesh ave been crystallographicallyc haracterized. The new syntheses of the three previously reported twisted acenes, decaphenylanthracene (1), 9,10,11,20,21,22-hexaphenyltetrabenzo[a,c,l,n]pentacene( 2), and 9, 10,11,12,13,14,15,16-octaphenyldibenzo[a,c]tetracene (14), resulted in ar eductiono ft he number of synthetic steps.A saconsequence their overall yields werei ncreased by factors of 50-, 24-, and 66-fold, respectively.A ll of the twisted acenes yntheses reported here are suitable fort he synthesis of at least gram quantities of these remarkable hydrocarbon materials.

High charge carrier mobilities have been greatly sought after in the development of cutting-edge organic electronic and optoelectronic devices. Although high field-effect transistor hole mobilities have been reported for solution-processed organic semiconductor thin films, their space-charge-limited current (SCLC) mobilities are still substantially lower. Herein, we report the synthesis and thin film SCLC hole mobilities of four polycyclic aromatic hydrocarbons, specifically, 2,5,8,17-tetra-tert-butyldiacenaphtho­[1,2-j:1′,2′-l]­fluoranthene (1), 2,5,8,11,14,17-hexa-tert-butyldiacenaphtho­[1,2-j:1′,2′-l]­fluoranthene (2), 2,9,12,15-tetra-tert-butylacenaphtho­[1,2-j]­benzo­[l]­fluoranthene (3), and 2,9,12,15-tetra-tert-butyl-4,5,6,7-tetraphenylacenaphtho­[1,2-j]­benzo­[l]­fluoranthene (4). Spin-coated pristine thin films of compounds 1–4 exhibit SCLC hole mobilities of 1.18 ± 0.18 × 10–3, 3.8 ± 0.9 × 10–5, 2.00 ± 0.87 × 10–3, and 2.27 ± 0.67 × 10–4 cm2 V–1 s–1, respectively. Upon thermal annealing at 120 °C for 10 min, compounds 1, 2, and 4 show limited changes in their optical properties and hole mobilities. In contrast, thermal annealing of thin films of 3 leads to broadened and red-shifted absorptions and emissions as well as drastically improved SCLC hole mobilities as high as 3.4 ± 0.1 × 10–1 cm2 V–1 s–1, one of the highest ever recorded SCLC hole mobilities on solution-processed organic semiconductor thin films. This improvement of the hole mobilities for the thin films of 3 is attributed to its radically enhanced crystallinity and intermolecular π–π overlap. Expansion of compound 3’s acene core with the hopes of further strengthening the π–π stacking interaction and thus further improving the SCLC mobility was unfortunately unsuccessful as the resulting molecule exhibits poor film formation properties.