Solution-processed solar cells are promising for the cost-effective, high-throughput production of photovoltaic devices. Colloidal quantum dots (CQDs) are attractive candidate materials for efficient, solution-processed solar cells, potentially realizing the broad-spectrum light utilization and multi-exciton generation effect for the future efficiency breakthrough of solar cells. The emerging quantum junction solar cells (QJSCs), constructed by n- and p-type CQDs only, open novel avenue for all-quantum-dot photovoltaics with a simplified device configuration and convenient processing technology. However, the development of high-efficiency QJSCs still faces the challenge of back carrier diffusion induced by the huge carrier density drop at the interface of CQDs and conductive glass substrate. Herein, an ultra-thin atomic layer deposited tin oxide (SnOx ) layer is employed to buffer this carrier density drop, significantly reducing the interfacial recombination and capacitance caused by the back carrier diffusion. The SnOx -modified QJSC achieves a record-high efficiency of 11.55% and a suppressed hysteresis factor of 0.04 in contrast with reference QJSC with an efficiency of 10.4% and hysteresis factor of 0.48. This work clarifies the critical effect of interfacial issues on the carrier recombination and hysteresis of QJSCs, and provides an effective pathway to design high-performance all-quantum-dot devices.
Keywords: capacitance effect; hysteresis; interfacial modification; quantum junction solar cells.
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