Quantum Dot/Polymer Bulk Heterostructure Interlayer for Enhanced Charge Collection in AgBiS2 Quantum Dot Photovoltaics

Abstract

Remarkable progress over the past decade in photovoltaics using solution-processed nanomaterials as light absorbers has placed colloidal quantum dot (CQD)-based devices on the map. As such, AgBiS2 CQDs have garnered significant attention as materials exhibiting a high absorptivity with environmentally benign alternatives to Pb-chalcogenide or Pb halide perovskite-CQDs. Yet, AgBiS2 CQD-based solar cells have gravely underperformed compared to Pb-containing devices, particularly in the metrics of charge carrier extraction from the AgBiS2 absorber, hence its relative mediocrity. To specifically address the extraction efficiency, a bulk heterostructure (QPB) interlayer at the CQD/polymer interface in AgBiS2 CQD solar cells, resulting in an increase of the power conversion efficiency (PCE), e.g., from 5.10% (an average PCE of 4.94 +/- 0.11%) to 6.78% (an average PCE of 6.59 +/- 0.11%) is deviced. The improved charge extraction at the hole-collecting interface is responsible for the superior performance, corroborated by high photocurrent (21.5 mA cm(-2)) and fill factor (67%). The QPB-interlayered solar cell also gives rise to outstanding durability of the devices, retaining above 95% of the original PCE for 5 months in ambient air. Our strategy based on an eco-friendly CQD/polymer could provide an effective route for next-generation optoelectronics with enhanced charge collection and durability.