A Dual‐Polythiophene Blending Strategy to Reduce the Efficiency‐Stability‐Cost Gap of Solar Cells

Abstract

Benefiting from the photovoltaic material innovation and delicate device optimization, high‐efficiency solar cells employing polymeric materials are thriving. Reducing the gap of cost, efficiency, and stability is the critical challenge faced by the emerging solar cells such as organics, quantum dots and perovskites. Poly(3‐alkylthiophene) demonstrates great potential in organic solar cells and quantum dot solar cells as the active layer or the hole transport layer due to its large scalability, excellent photoelectric performance, and favorable hydrophobicity. The present low efficiency and insufficient stability, restrict its commercial application. In this work, a facile strategy of blending two simple polythiophenes is put forward to manipulate the film microstructure and enhance the device efficiency and thermal stability of solar cells. The introduction of P3PT can improve the power conversion efficiency (PCE) of a benchmark cost‐effective blend P3HT:O‐IDTBR to 7.41%, and the developed ternary solar cells also exhibit increased thermal stability. More strikingly, the quantum dot solar cells with the dual‐polythiophene hole transport layer achieve the highest PCE of 10.51%, which is among the topmost efficiencies for quantum dots/polythiophene solar cells. Together, this work provides an effective route to simultaneously optimize the device efficiency and thermal stability of solar cells.

Tuning the Aggregated Structure of Polymer Interlayers for High-Performance Quantum Dot Solar Cells and Photodetectors

“…For QD optoelectronic devices, substantial donor polymers can be employed for hole transport, e.g., polythiophenes and other conjugated polymers. − It is well established that the classical polythiophene material, P3HT, generally presents strong molecular aggregation and edge-on stacking, − which result in unfavorable hole transport and an inferior optoelectronic performance. Moreover, the high energy landscape of P3HT also leads to a mismatch with PbS QDs, which places great restrictions on the further performance enhancement of QD/P3HT solar cells. , In order to tackle these concerns, our group has developed various strategies to modulate the molecular aggregation and energy landscape of polythiophenes for QD photovoltaic and photodetection devices. ,, Our group recently reported that o -xylene-processed P3HT presents moderate morphology and characteristic lengths, resulting in an increasing PCE to ∼8.7% for QD solar cells . In addition, our most recent study demonstrated that poly(3-pentylthiophene) (P3PT) could achieve decreased molecular aggregation and advantageous face-on orientation (Figure c–e), enabling a remarkable PCE enhancement of QD devices and perovskite-based devices from ∼8.6% to ∼9.5% and from ∼16% to ∼18.8%, respectively.…”

“…Inspired by the success of dual polymer blending in donor–acceptor (D–A) conjugated polymers, our group further developed the blending HTLs based on P3HT-Br and P3HT and realized a high efficiency of 11% (Figure e–g) . A very recent work by Qi et al reported another case of dual-polythiophene blending based on two simple polythiophenes (P3HT and P3PT) . Specifically, two simple polythiophenes (P3HT and P3PT) with distinct solution aggregation features (as reflected in their persistence lengths) were blended to tune the film microstructure.…”

“…29,54 In order to tackle these concerns, our group has developed various strategies to modulate the molecular aggregation and energy landscape of polythiophenes for QD photovoltaic and photodetection devices. 40,41,55 Our group recently reported that o-xylene-processed P3HT presents moderate morphology and characteristic lengths, resulting in an increasing PCE to ∼8.7% for QD solar cells. 55 In addition, our most recent study demonstrated that poly(3-pentylthiophene) (P3PT) could achieve decreased molecular aggregation and advantageous face-on orientation (Figure 3c−e), enabling a remarkable PCE enhancement of QD devices and perovskite-based devices from ∼8.6% to ∼9.5% and from ∼16% to ∼18.8%, respectively.…”

“…Moving forward, the other two sets of photovoltaic polymers are used to confirm the efficacy of this approach successfully (Figure 5d). Hence, the 41 Specifically, two simple polythiophenes (P3HT and P3PT) with distinct solution aggregation features (as reflected in their persistence lengths) were blended to tune the film microstructure. In addition to the device's PCE of solar cells, the thermal stability can also be improved.…”

“…They subsequently developed a new organic HTL with the desirable face-on orientation stacking, which can enable enhanced carrier extraction and a superior photovoltaic performance . Our group has developed various strategies to modulate the aggregation of organic HTLs for QD optoelectronic devices and enhanced the photovoltaic and photodetection performances to ∼14% and over 10 13 Jones in a near-infrared band, respectively. ,,− Generally, due to the beneficial morphology and molecular stacking originating from aggregation regulation, the optoelectronic properties of organic HTLs can be regulated, particularly in terms of hole mobility.…”