Conjugated polymers enable the production of flexible semiconductor devices that can be processed from solution at low temperatures. Over the past 25 years, device performance has improved greatly as a wide variety of molecular structures have been studied. However, one major limitation has not been overcome; transport properties in polymer films are still limited by pervasive conformational and energetic disorder. This not only limits the rational design of materials with higher performance, but also prevents the study of physical phenomena associated with an extended π-electron delocalization along the polymer backbone. Here we report a comparative transport study of several high-mobility conjugated polymers by field-effect-modulated Seebeck, transistor and sub-bandgap optical absorption measurements. We show that in several of these polymers, most notably in a recently reported, indacenodithiophene-based donor-acceptor copolymer with a near-amorphous microstructure, the charge transport properties approach intrinsic disorder-free limits at which all molecular sites are thermally accessible. Molecular dynamics simulations identify the origin of this long sought-after regime as a planar, torsion-free backbone conformation that is surprisingly resilient to side-chain disorder. Our results provide molecular-design guidelines for 'disorder-free' conjugated polymers.

sources at 1000 lux had an irradiance of 340 and 320 µW cm −2 , respectively. The accuracy of the light meter and power meter is the primary determinant of the uncertainty in the measured PCE values, which amounts to approximately ±6-7%, as can be determined from a straightforward uncertainty analysis based on the device testing conditions and the specifications of the power and light meters. Consequently, the PCE values are reported herein with 1 decimal place.

A general semiconductor‐independent two‐dimensional character of the carrier distribution in top‐gate polymer field‐effect transistors is revealed by analysing temperature‐dependent transfer characteristics and the sub‐bandgap absorption tails of the polymer semiconductors. A correlation between the extracted width of the density of states and the Urbach energy is presented, corroborating the 2D accumulation layer and demonstrating an intricate connection between optical measurements concerning disorder and charge transport in transistors.

The Internet of Things (IoT) provides everyday objects and environments with “intelligence” and data connectivity to improve quality of life and the efficiency of a wide range of human activities. However, the ongoing exponential growth of the IoT device ecosystem—up to tens of billions of units to date—poses a challenge regarding how to power such devices. This Progress Report discusses how energy harvesting can address this challenge. It then discusses how indoor photovoltaics (IPV) constitutes an attractive energy harvesting solution, given its deployability, reliability, and power density. For IPV to provide an eco‐friendly route to powering IoT devices, it is crucial that its underlying materials and fabrication processes are low‐toxicity and not harmful to the environment over the product life cycle. A range of IPV technologies—both incumbent and emerging—developed to date is discussed, with an emphasis on their environmental sustainability. Finally, IPV based on emerging lead‐free perovskite‐inspired absorbers are examined, highlighting their status and prospects for low‐cost, durable, and efficient energy harvesting that is not harmful to the end user and environment. By examining emerging avenues for eco‐friendly IPV, timely insight is provided into promising directions toward IPV that can sustainably power the IoT revolution.

All-inorganic perovskite light-emitting diodes (LEDs) reveal efficient luminescence with high color purity, but their modest brightness and poor stability are still critical drawbacks. Here, the luminescent efficiency and the stability of perovskite LEDs (PeLEDs) are boosted by antisolvent vapor treatment of CsPbBr 3 embedded in a dielectric polymer matrix of polyethylene oxide (PEO). A unique method is developed to obtain high quality CsPbBr 3 emitting layers with low defects by controlling their grain sizes. CsPbBr 3 in PEO matrix is post-treated with antisolvent of chloroform (CF), leading to microcrystals with a size of ≈5 µm along the in-plane direction with active emitting composite of 90%. A device based on CF post-treatment (CsPbBr 3 -PEO-CF) film displays a brightness of up to 51890 cd m −2 with an external quantum efficiency of 4.76%. CsPbBr 3 -PEO-CF PeLED still maintains 82% of its initial efficiency after 80 h continuous operation in ambient air, which indicates relatively good device stability. This work highlights that film quality is not only key to promoting fluorescence in CsPbBr 3 , but also to achieving higher performance PeLEDs.