In　perovskite　solar　cells　(PSCs),　the　interfaces　are　a　weak　link　with　respect　to　degradation.　Electrochemical　reactivity　of　the　perovskite＇s　halides　has　been　reported　for　both　molecular　and　polymeric　hole　selective　layers　(HSLs),　and　here　it　is　shown　that　also　NiO　brings　about　this　decomposition　mechanism.　Employing　NiO　as　an　HSL　in　p–i–n　PSCs　with　power　conversion　efficiency　(PCE)　of　16.8%,　noncapacitive　hysteresis　is　found　in　the　dark,　which　is　attributable　to　the　bias-induced　degradation　of　perovskite/NiO　interface.　The　possibility　of　electrochemically　decoupling　NiO　from　the　perovskite　via　the　introduction　of　a　buffer　layer　is　explored.　Employing　a　hybrid　magnesium-organic　interlayer,　the　noncapacitive　hysteresis　is　entirely　suppressed　and　the　device＇s　electrical　stability　is　improved.　At　the　same　time,　the　PCE　is　improved　up　to　18%　thanks　to　reduced　interfacial　charge　recombination,　which　enables　more　efficient　hole　collection　resulting　in　higher　Voc　and　FF.　©　2019　WILEY-VCH　Verlag　GmbH　&　Co.　KGaA,　Weinheim